Lucy had 2200 mℓ more soy milk than Marion. After Lucy gave Marion 590 mℓ of soy milk, the ratio of Lucy's soy milk to Marion's soy milk became 7 : 4. How much soy milk did Lucy have at first? Give your answer in millilitres.
|
Lucy |
Marion |
Difference |
Before |
1 u + 2200 |
1 u |
2200 |
Change |
- 590 |
+ 590 |
|
After |
1 u + 1610 |
1 u + 590 |
1020 |
Comparing Lucy and Marion in the end |
7 p |
4 p |
3 p |
Volume of soy milk that Lucy had in the end
= 1 u + 2200 - 590
= 1 u + 1610
Difference in the volume of soy milk between Lucy and Marion in the end
= 7 p - 4 p
= 3 p
3 p = 1610 - 590
3 p = 1020
1 p = 1020 ÷ 3 = 340
Volume of soy milk that Lucy had at first
= 7 p + 590
= 7 x 340 + 590
= 2380 + 590
= 2970 mℓ
Answer(s): 2970 mℓ