Penelope purchased a bottle of oil. She used ⁴₇ of the oil in March. She then used the remaining oil in April and May in the ratio 3 : 4. Given that the amount of the oil used in May was 0.48 ℓ less than that in March, how many millilitres of oil did the bottle contain at first?

March	April	May	Total
4x7	3x7		7x7
	3x3	4x3
28 u	9 u	12 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 less oil syrup in the bottle used in May than March
= 28 u - 12 u
= 16 u

16 u = 0.48 

1 u = 0.48 ÷ 16 = 0.03

Amount of oil in the bottle at first
= 49 u
= 49 x 0.03
= 1.47 ℓ

1 ℓ = 1000 mℓ

Amount of oil in the bottle at first
= 1.47 x 1000
= 1470 mℓ

Answer(s): 1470 mℓ