45-2×(15-3) Please Help me figure this out because my calculator says the answer is 21 but I don't know why

Answer:
see explanation
Step-by-step explanation:
Following the order of operations as set out in PEMDAS
Given
45 - 2 × (15 - 3) ← evaluate parenthesis
= 45 - 2 × 12 ← evaluate multiplication
= 45 - 24 ← evaluate subtraction
= 21