Tammy purchased a bottle of pomegranate syrup to make drinks. She used ⁴₇ of the syrup in March. She then used the remaining syrup in April and May in the ratio 1 : 6. Given that the amount of the pomegranate syrup used in March was 1 ℓ more than that in April, how many millilitres of pomegranate syrup did the bottle contain at first?

March	April	May	Total
4x7	3x7		7x7
	1x3	6x3
28 u	3 u	18 u	49 u

Total volume of April and May is combined repeated identity.  Make the total volume of April and May the same.  LCM of 3 and 7 is 21.

Volume of more pomegranate syrup in the bottle used in March than April
= 28 u - 3 u
= 25 u

25 u = 1 

1 u = 1 ÷ 25 = 0.04

Amount of pomegranate syrup in the bottle at first
= 49 u
= 49 x 0.04
= 1.96 ℓ

1 ℓ = 1000 mℓ

Amount of pomegranate syrup in the bottle at first
= 1.96 x 1000
= 1960 mℓ

Answer(s): 1960 mℓ