Which calculations correctly identify an original value from a final value? Select all that apply.
After a 20% rise to 144, the original was 144 / 1.20 = 120.✓Bonne réponse
After a 10% fall to 135, the original was 135 / 0.90 = 150.✓Bonne réponse
After 30% off gives 56, the original was 56 × 1.30 = 72.80.
After a 20% rise to 84, the original was 84 × 1.20 = 100.80.
Explication
Dividing 144 by 1.20 gives 120, and dividing 135 by 0.90 gives 150, so both correctly undo the stated change. Adding 30% to 56 or multiplying 84 by 1.20 adjusts the final value instead of reversing its multiplier.