Opal had 1310 mℓ more coffee than Risa. After Opal gave Risa 430 mℓ of coffee, the ratio of Opal's coffee to Risa's coffee became 7 : 4. How much coffee did Opal have at first? Give your answer in millilitres.
|
Opal |
Risa |
Difference |
Before |
1 u + 1310 |
1 u |
1310 |
Change |
- 430 |
+ 430 |
|
After |
1 u + 880 |
1 u + 430 |
450 |
Comparing Opal and Risa in the end |
7 p |
4 p |
3 p |
Volume of coffee that Opal had in the end
= 1 u + 1310 - 430
= 1 u + 880
Difference in the volume of coffee between Opal and Risa in the end
= 7 p - 4 p
= 3 p
3 p = 880 - 430
3 p = 450
1 p = 450 ÷ 3 = 150
Volume of coffee that Opal had at first
= 7 p + 430
= 7 x 150 + 430
= 1050 + 430
= 1480 mℓ
Answer(s): 1480 mℓ