PSLE
Erika had a bottle of coffee. She drank 1120 mℓ of coffee in the afternoon and ²₅ of remaining coffee in the evening. After that, there was ¹₇ a bottle of coffee left. How much of the coffee did she drink in the evening?
Fraction of the remaining coffee left in the end
= 1 - ²₅
= ³₅

The remaining coffee left in the end is equal to ¹₇ of the bottle of coffee.
Make numerators the same.
LCM of 3 and 1 is 3.
 
³₅ of the remaining coffee = ¹₇ of the total coffee
³₅ of the remaining coffee = ³₂₁ of the total coffee

Volume of coffee that she drank in the afternoon
= 21 u - 5 u
= 16 u

16 u = 1120

1 u = 1120 ÷ 16 = 70

Volume of coffee that she drank in the evening
= 2 u
= 2 x 70
= 140 mℓ

Answer(s): 140 mℓ