Xuan had 1780 mℓ more soy milk than Zara. After Xuan gave Zara 490 mℓ of soy milk, the ratio of Xuan's soy milk to Zara's soy milk became 7 : 3. How much soy milk did Xuan have at first? Give your answer in millilitres.
|
Xuan |
Zara |
Difference |
Before |
1 u + 1780 |
1 u |
1780 |
Change |
- 490 |
+ 490 |
|
After |
1 u + 1290 |
1 u + 490 |
800 |
Comparing Xuan and Zara in the end |
7 p |
3 p |
4 p |
Volume of soy milk that Xuan had in the end
= 1 u + 1780 - 490
= 1 u + 1290
Difference in the volume of soy milk between Xuan and Zara in the end
= 7 p - 3 p
= 4 p
4 p = 1290 - 490
4 p = 800
1 p = 800 ÷ 4 = 200
Volume of soy milk that Xuan had at first
= 7 p + 490
= 7 x 200 + 490
= 1400 + 490
= 1890 mℓ
Answer(s): 1890 mℓ