Eva purchased a bottle of guava 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 1 : 6. Given that the amount of the guava syrup used in January was 0.69 ℓ more than that in February, how many millilitres of guava syrup did the bottle contain at first?

January	February	March	Total
4x7	5x7		9x7
	1x5	6x5
28 u	5 u	30 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 guava syrup in the bottle used in January than February
= 28 u - 5 u
= 23 u

23 u = 0.69 

1 u = 0.69 ÷ 23 = 0.03

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

1 ℓ = 1000 mℓ

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

Answer(s): 1890 mℓ