Gem purchased a bottle of mango syrup to make drinks. She used ³₈ of the syrup in April. She then used the remaining syrup in May and June in the ratio 1 : 2. Given that the amount of the mango syrup used in April was 0.28 ℓ more than that in May, how many millilitres of mango syrup did the bottle contain at first?

April	May	June	Total
3x3	5x3		8x3
	1x5	2x5
9 u	5 u	10 u	24 u

Total volume of May and June is combined repeated identity.  Make the total volume of May and June the same.  LCM of 5 and 3 is 15.

Volume of more mango syrup in the bottle used in April than May
= 9 u - 5 u
= 4 u

4 u = 0.28 

1 u = 0.28 ÷ 4 = 0.07

Amount of mango syrup in the bottle at first
= 24 u
= 24 x 0.07
= 1.68 ℓ

1 ℓ = 1000 mℓ

Amount of mango syrup in the bottle at first
= 1.68 x 1000
= 1680 mℓ

Answer(s): 1680 mℓ