PSLE
Barbara had a bottle of soy milk. She drank 880 mℓ of soy milk in the morning and ³₅ of remaining soy milk in the evening. After that, there was ¹₈ a bottle of soy milk left. How much of the soy milk did she drink in the evening?
Fraction of the remaining soy milk left in the end
= 1 - ³₅
= ²₅

The remaining soy milk left in the end is equal to ¹₈ of the bottle of soy milk.
Make numerators the same.
LCM of 2 and 1 is 2.
 
²₅ of the remaining soy milk = ¹₈ of the total soy milk
²₅ of the remaining soy milk = ²₁₆ of the total soy milk

Volume of soy milk that she drank in the morning
= 16 u - 5 u
= 11 u

11 u = 880

1 u = 880 ÷ 11 = 80

Volume of soy milk that she drank in the evening
= 3 u
= 3 x 80
= 240 mℓ

Answer(s): 240 mℓ