This is a working backwards problem. You know he has $35 at the end. Before he gave his brother $5, he would have $40, which is half of what he had before he bought the clothes, so he would have had $80. Before he spent the $40 on shoes, he would have had $120, so the answer is $120.
(x + y)^2 = (x^2 - 2xy + y^2)
First distribute the ^2 on the left side of the equation to each term inside the parenthesis:
x^2+ 2xy + y^2
Now pick one of the variables to solve for and isolate it:
(solving for x)
x^2 + 2xy + y^2 = x^2 - 2xy + y^2
x^2+ 2xy = x^2 - 2xy
2xy = -2xy
-x = x
x = 0
When you solve for y in the equation it will turn out to be 0 as well
The answer is C. U just have to divide 7 and 12 to get your decimal