PSLE
Esther had a bottle of soy milk. She drank 1050 mℓ of soy milk in the morning and ³₇ of remaining soy milk in the afternoon. After that, there was ¹₇ a bottle of soy milk left. How much of the soy milk did she drink in the afternoon?
Fraction of the remaining soy milk left in the end
= 1 - ³₇
= ⁴₇

The remaining soy milk left in the end is equal to ¹₇ of the bottle of soy milk.
Make numerators the same.
LCM of 4 and 1 is 4.
 
⁴₇ of the remaining soy milk = ¹₇ of the total soy milk
⁴₇ of the remaining soy milk = ⁴₂₈ of the total soy milk

Volume of soy milk that she drank in the morning
= 28 u - 7 u
= 21 u

21 u = 1050

1 u = 1050 ÷ 21 = 50

Volume of soy milk that she drank in the afternoon
= 3 u
= 3 x 50
= 150 mℓ

Answer(s): 150 mℓ