No.
The sum of the areas of the two smaller squares is 5^2 + 3^2 = 34
The area of the larger square is 8^2=64
34 does not = 64

We're dividing fractions, so we will flip the one in the denominator upside down and we will multiply it with the numerator.

Let's equal this too 8/x

Cross multiply.

Divide both sides by 15.
11) 7 + -10+(4(5+-3)) = 7+-10+8=5
12) (12 +-10)+3x+-1(2x+4x), 12+-10x+3x+-2x+-4x = 12+-13x