I've gotten stuck trying to solve the equation below for y. It's a tricky one for me as my algebra skills are basic at best.
I have managed to get somewhere but the answer that comes out of the final equation is about 17% error from starting equation when I plug some numbers into it.
Have I missed something or is there a better way?
Start with 2 equations:
 and

Need to substitute equation 2 into 1 and solve for y. Then resubstitute and solve for x. (Only r, w, and d are known).
I got to this:
3.
But this leaves me with
on the RHS under the square root. From here is were I am unsure.
I managed to get to this:
4.
This got rid of y and x from RHS however, when I input some values to check if it works I get a different value for y between equations 3 and 4.
Values I used are:
r=3
w=12
d=11
x=4
y=5
(had to use a number for y in eq. 3 to check it works)
Same numbers in eq.4 y = 4.341?
Have I gone about this the right way? what am I missing?
Thanks.