PSLE
Tiffany had a bottle of orange juice. She drank 1200 mℓ of orange juice in the afternoon and ²₇ 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 - ²₇
= ⁵₇

The remaining orange juice left in the end is equal to ¹₃ of the bottle of orange juice.
Make numerators the same.
LCM of 5 and 1 is 5.
 
⁵₇ of the remaining orange juice = ¹₃ of the total orange juice
⁵₇ of the remaining orange juice = ⁵₁₅ of the total orange juice

Volume of orange juice that she drank in the afternoon
= 15 u - 7 u
= 8 u

8 u = 1200

1 u = 1200 ÷ 8 = 150

Volume of orange juice that she drank at night
= 2 u
= 2 x 150
= 300 mℓ

Answer(s): 300 mℓ