70 percent off 150

70% off 150 is 45

150 minus 70 percent off is 45

The discount itself is 105: 150 × 70 ÷ 100 = 105. Taking it off 150 leaves 45.

Only approximately: 45 ÷ 0.3 = 150. The discount is rounded to the cent, so several prices give the same 45 — 149.99 (discount 104.99), 150 (discount 105) and 150.01 (discount 105.01); the paid price alone cannot tell them apart.