Tiffany purchased a bottle of mango syrup to make drinks. She used ⁴₉ of the syrup in January. She then used the remaining syrup in February and March in the ratio 2 : 5. Given that the amount of the mango syrup used in January was 0.54 ℓ more than that in February, how many millilitres of mango syrup did the bottle contain at first?

January	February	March	Total
4x7	5x7		9x7
	2x5	5x5
28 u	10 u	25 u	63 u

Total volume of February and March is combined repeated identity.  Make the total volume of February and March the same.  LCM of 5 and 7 is 35.

Volume of more mango syrup in the bottle used in January than February
= 28 u - 10 u
= 18 u

18 u = 0.54 

1 u = 0.54 ÷ 18 = 0.03

Amount of mango syrup in the bottle at first
= 63 u
= 63 x 0.03
= 1.89 ℓ

1 ℓ = 1000 mℓ

Amount of mango syrup in the bottle at first
= 1.89 x 1000
= 1890 mℓ

Answer(s): 1890 mℓ