Gwen purchased a bottle of vinegar. She used ³₅ of the vinegar in February. She then used the remaining vinegar in March and April in the ratio 1 : 4. Given that the amount of the vinegar used in April was 0.49 ℓ less than that in February, how many millilitres of vinegar did the bottle contain at first?

February	March	April	Total
3x5	2x5		5x5
	1x2	4x2
15 u	2 u	8 u	25 u

Total volume of March and April is combined repeated identity. Make the total volume of March and April the same. LCM of 2 and 5 is 10.

Volume of less vinegar syrup in the bottle used in April than February
= 15 u - 8 u
= 7 u

7 u = 0.49 

1 u = 0.49 ÷ 7 = 0.07

Amount of vinegar in the bottle at first
= 25 u
= 25 x 0.07
= 1.75 ℓ

1 ℓ = 1000 mℓ

Amount of vinegar in the bottle at first
= 1.75 x 1000
= 1750 mℓ

Answer(s): 1750 mℓ