PSLE
Fanny had a bottle of orange juice. She drank 550 mℓ of orange juice in the afternoon and ³₇ of remaining orange juice at night. After that, there was ¹₃ a bottle of orange juice left. How much of the orange juice did she drink at night?
Fraction of the remaining orange juice left in the end
= 1 - ³₇
= ⁴₇

The remaining orange juice left in the end is equal to ¹₃ of the bottle of orange juice.
Make numerators the same.
LCM of 4 and 1 is 4.
 
⁴₇ of the remaining orange juice = ¹₃ of the total orange juice
⁴₇ of the remaining orange juice = ⁴₁₂ of the total orange juice

Volume of orange juice that she drank in the afternoon
= 12 u - 7 u
= 5 u

5 u = 550

1 u = 550 ÷ 5 = 110

Volume of orange juice that she drank at night
= 3 u
= 3 x 110
= 330 mℓ

Answer(s): 330 mℓ