45/45/90 triangle has side ratios s/s/sroot2
leg = root 5
Other leg is also root 5
X is Hypotenuse which would be root 5 * root 2
root 5*2 = root 10
You need to have variables one one side and constants on the other. ax - ax + by = c - ax
by = c - ax
by/b = (c - ax)/b
y = (c - ax)/b