PSLE
Mrs Tan had a bottle of wine. She used an equal amount of wine each day. At the end of the eighth day, she had 700 mℓ of wine left. At the end of the twelfth day, she had one-third of the bottle of wine left. How many litres of wine were there in the bottle at first?
Fraction of wine used after one-third of the bottle was left
= 1 - ¹₃
= ²₃

²₃ of the bottle → 12 days
1 bottle → 12 ÷ ²₃ = 12 x ³₂ =  18 days

It takes 18 days to finish the whole bottle.

Number of days to use 700 mℓ of wine
= 18 - 8
= 10

10 days → 700 mℓ

1 day → 700 ÷ 10 = 70 mℓ

18 days → 18 x 70 = 1260 mℓ

1000 mℓ = 1 ℓ

1260 mℓ = 1260 ÷ 1000 = 1.26 ℓ

Volume of wine in the bottle at first = 1.26 ℓ

Answer(s): 1.26 ℓ