we have the expression
1/2 (4×5)-2³
so
Applying PEMDAS
P ----> Parentheses first
E -----> Exponents (Powers and Square Roots, etc.)
MD ----> Multiplication and Division (left-to-right)
AS ----> Addition and Subtraction (left-to-right)
step 1
Parentheses first
(4x5)=20
substitute
1/2*20-2³
step 2
Exponents
2³=8
substitute
1/2*20-8
step 3
Multiplication
1/2*20=10
substitute
10-8
step 4
Subtraction
10-8=2
answer is 2