Calculating the depth of flow in an open channel

Hi guys, I am still learning this software.

I am trying to use trial and error to find the solution of depth (Y) in open channels using mathcad solver block. I have set all guess values and
constraints, how best can i solve this?

Or is there another way of determining the value of Y.

I have also attached the original question with step by step calculations and correct answers, in case one needs
to restart everything.

I appreciate your input and comments.

Thank you in advance.