Answer :

You must use PEMDAS.

12 ÷ 2 × 2³ = 120
12 ÷ 2 × 8 = 120
6 × 8 = 120
48 ≠ 120
If you solve without parentheses, it does not equal 120.

(12 ÷ 2) × 2³ = 120
6 × 2³ = 120
6 × 8 = 120
48 ≠ 120
If you put the parentheses around 12 ÷ 2, it does not equal 120.

12 ÷ (2 × 2³) = 120
12 ÷ (2 × 8) = 120
12 ÷ 16 = 120
0.75 ≠ 120
If you put the parentheses around 2 × 2³, it does not equal 120.

(12 ÷ 2 × 2)³ = 120
(6 × 2)³ = 120
(12)³ = 120
1728 ≠ 120
If you put the parentheses around 12 ÷ 2 × 2, it does not equal 120.

You cannot put parentheses anywhere to get the answer of 120.