Evaluate 15 − 4 + (7 − 5)2

a.) 15

b.) 13

c.) 21

d.) 23

I'm assuming the last number is an exponent. Lets us PEMDAS

Start off with the parenthesis 

15 - 4 + (7 - 5)^2

15 - 4 + 2^2

Next is exponenets

15 - 4 + 4

Now we add and subtract from left to right.

15 - 4 + 4

11 + 4

15 (A) is the final answer.

To determine which operation is the top priority, follow PEMDAS. This means that those inside the Parenthesis are the top priority. This is followed by Exponents, Multiplication, Division, Addition and lastly, Subtraction.So,

15 − 4 + (7 − 5)2
15 - 4 + (2)(2)
15 - 4 + 4
15 - 0
15

Therefore, the answer is A.