Betty had 2200 mℓ more soy milk than Ivory. After Betty gave Ivory 420 mℓ of soy milk, the ratio of Betty's soy milk to Ivory's soy milk became 7 : 3. How much soy milk did Betty have at first? Give your answer in millilitres.
|
Betty |
Ivory |
Difference |
Before |
1 u + 2200 |
1 u |
2200 |
Change |
- 420 |
+ 420 |
|
After |
1 u + 1780 |
1 u + 420 |
1360 |
Comparing Betty and Ivory in the end |
7 p |
3 p |
4 p |
Volume of soy milk that Betty had in the end
= 1 u + 2200 - 420
= 1 u + 1780
Difference in the volume of soy milk between Betty and Ivory in the end
= 7 p - 3 p
= 4 p
4 p = 1780 - 420
4 p = 1360
1 p = 1360 ÷ 4 = 340
Volume of soy milk that Betty had at first
= 7 p + 420
= 7 x 340 + 420
= 2380 + 420
= 2800 mℓ
Answer(s): 2800 mℓ