PSLE
Irene had a bottle of coffee. She drank 900 mℓ of coffee in the morning and ³₅ of remaining coffee in the afternoon. After that, there was ¹₇ a bottle of coffee left. How much of the coffee did she drink in the afternoon?
Fraction of the remaining coffee left in the end
= 1 - ³₅
= ²₅

The remaining coffee left in the end is equal to ¹₇ of the bottle of coffee.
Make numerators the same.
LCM of 2 and 1 is 2.
 
²₅ of the remaining coffee = ¹₇ of the total coffee
²₅ of the remaining coffee = ²₁₄ of the total coffee

Volume of coffee that she drank in the morning
= 14 u - 5 u
= 9 u

9 u = 900

1 u = 900 ÷ 9 = 100

Volume of coffee that she drank in the afternoon
= 3 u
= 3 x 100
= 300 mℓ

Answer(s): 300 mℓ