Jen purchased a bottle of passion fruit syrup to make drinks. She used ¹₃ of the syrup in March. She then used the remaining syrup in April and May in the ratio 2 : 5. Given that the amount of the passion fruit syrup used in March was 0.18 ℓ more than that in April, how many millilitres of passion fruit syrup did the bottle contain at first?

March	April	May	Total
1x7	2x7		3x7
	2x2	5x2
7 u	4 u	10 u	21 u

Total volume of April and May is combined repeated identity.  Make the total volume of April and May the same.  LCM of 2 and 7 is 14.

Volume of more passion fruit syrup in the bottle used in March than April
= 7 u - 4 u
= 3 u

3 u = 0.18 

1 u = 0.18 ÷ 3 = 0.06

Amount of passion fruit syrup in the bottle at first
= 21 u
= 21 x 0.06
= 1.26 ℓ

1 ℓ = 1000 mℓ

Amount of passion fruit syrup in the bottle at first
= 1.26 x 1000
= 1260 mℓ

Answer(s): 1260 mℓ