Follow your order of operations rules: PEMDAS (Parenthesis, Exponents, Multiply, Divide, Add, Subtract)
There are no parenthesis, so look to the exponent:
6^2 = A
There's no multiplication, but there's:
-8÷2 = B
So now combine those two, so that A+B = ? (Remember, B will have a negative value, so when you add a negative number, you actually subtract its value.)