百分率方程

設共有 y 毫升,
(y x 18%) + (y x 22%) = 960
y x (18% + 22%) = 960
y x 40% = 960
y x 40/100 = 960
y = 960 x 100/40
y = 2400

還餘 y - 960 = 2400 - 960 = 1440 毫升

1440ml

共喝去的 18%+22% = 40% = 960 ml
即總共有 960 / 40% = 2400 ml
現餘下橙汁有 2400 x (100% - 40%)= 1440 (ml)