Thank you very much Luc for the thorough explanation. I will follow your advice, I will keep you all posted with the results.
Some extra tips.
In the example I copied a number of Mathcad regions and pasted it/them into the Word document. This becomes one picture in Word.
If you copy one single (math or text or other) region from the Mathcad sheet and paste it into your Word document (as a windows metafile picture of course) it becomes a picture by itself in that document. Copy another region from Mathcad and paste it into the Word document gets you another picture. Now depending on the sizes of these (Mathcad) regions, these pictures may show their content in different sizes in your Word document.
What I often do is embed the Mathcad equations in a (Mathcad) text region, and I make sure that the Mathcad text region is set to 'occupy page width'. That is a property for a text region that you can set.
Now copying those text regions and pasting them into the Word document will make sure they are all the same width (the height may differ), and this will make it easier to ensure that the pictures in Word show their equations and other stuff as much as possible in the same proportions that they have in Mathcad.
But embedding math in text regions in Mathcad has its limitations. You cannot embed a graph into a text region in Mathcad. I suggest you make sure your math (and graph and picture and other regions) are no wider than the Mathcad page width (= the width of the 'occupy page width' text regions). Now you should be able to easily keep proportions in your Word document if you copy with every (set of) Mathcad regions at least one such 'occupy page width' text region over. You'll probably have explanatory text interleaved with your equations, graphs etc., so there should be no problem having an 'occupy page width' text region close to any (set of) region(s) that you need to copy over.
Now in Word you can set the attributes of the resulting pictures to all have the same width to ensure equal proportions for everything copied over from Mathcad in the above described manner. This way you force the 'Mathcad page width' become equal to the width of the pictures you set in Word. Note that when you paste a picture on an empty line in Word, (most often) it will be scaled to occupy the text width in your Word document. If that is suitable for all you need to bring over, you don't have to set the width for every picture individually.
In short: with a little preparation, you should be able to copy Mathcad content to a Word document without (too) much hassle AND get presentable results.
thanks Luck for your explicit explanation.
To making the long story short, I prepare a book for corrosion protection (cathodic protection theory) with new equations and how to use them. So, the book is in the hands of the publisher to complete the final review. Them came to me saying that the equations were not having the dpi required. You already know the other side of the story.
Now, changing equation by equation in the book would be a cumbersome task.
I have learned from each of the advices I have received here and what I ended up doing few hours ago is as follow:
1) I created a pdf of a complete chapter, as they are right now.
2) I exported the pdf to TIFF file, the chapter was automatically separated per pages, each page being a TIFF file, when I checked the dpi of the TIFF files it was already 200 dpi.
3) I found a web site: https://convert.town, where you can select what dpi you want and you only have to upload the image file (in this case each of my TIFF files) and it converts the files automatically to the dpi to chose. I chose 300 dpi. And this worked perfect, it seems. I check the dpi of the new converted TIFF and it has the 300 dpi required by the publisher company.
I have sent them two pages, one with text and graphs and one with text and equations.
I will let you know what the outcome is.
Again, thank you very much to all of you that helped me on this subject, this is the last "stone" (it seems) to have my book published.
the method I explained later did not work, even the entire page had 300 dpi, the equations still looked fuzzy.
what at the end I had to do is copy and paste each equation again.
I copy from Mathcad and use the paste special in word as follow: paste special>paste link>picture (windows metafile).
This is the only way I found to paste as windows metafile in word. After few paste equations, I have brake the links that are created, but this way has created the best quality, the editor, at last accepted this quality.
in the case of the figures, the editor was ok receiving the pictures separately in jpg format and he will put them where they belong. When I tried to insert the figures (that were created in Autocad) directly in my word document, they do not look good.
thank you to all for your help.