Yoko had 2120 mℓ more milk than Ivory. After Yoko gave Ivory 490 mℓ of milk, the ratio of Yoko's milk to Ivory's milk became 7 : 4. How much milk did Yoko have at first? Give your answer in millilitres.
|
Yoko |
Ivory |
Difference |
Before |
1 u + 2120 |
1 u |
2120 |
Change |
- 490 |
+ 490 |
|
After |
1 u + 1630 |
1 u + 490 |
1140 |
Comparing Yoko and Ivory in the end |
7 p |
4 p |
3 p |
Volume of milk that Yoko had in the end
= 1 u + 2120 - 490
= 1 u + 1630
Difference in the volume of milk between Yoko and Ivory in the end
= 7 p - 4 p
= 3 p
3 p = 1630 - 490
3 p = 1140
1 p = 1140 ÷ 3 = 380
Volume of milk that Yoko had at first
= 7 p + 490
= 7 x 380 + 490
= 2660 + 490
= 3150 mℓ
Answer(s): 3150 mℓ