help to solve equations

Apart from the typo you made there is a general problem in your solve block.

You are just solving for one variable (v1) but you provide four equations.

In trying to get a solution Mathcad will only try to change v1 and none of the other values.

So the two "effect formula" equations will have no effect as they do not contain v1, but the "constant slip relation" equation and the "Admirality coefficient" equation are contradictory.

The first would yield v1=20, but second gives us v1=23.331 (approx.). So the solve block is not able to find a solution.

So you will have to decide which values are allowed to be changed, too, and you have to solve for those values as well, simultaneously to v1.

You may solve for less than four values but you will have to solve at least for two of them to get a solution.

On second look...

Mathcad can solve hundreds of simultaneous equations, BUT....

You have to make sure that they do not contradict.

In your case you have:

And all that while you have the two delta's defined to be different.

Check your equations...

Success!
Luc