Pamela had 2580 mℓ more coffee than Betty. After Pamela gave Betty 510 mℓ of coffee, the ratio of Pamela's coffee to Betty's coffee became 7 : 3. How much coffee did Pamela have at first? Give your answer in millilitres.
| |
Pamela |
Betty |
Difference |
| Before |
1 u + 2580 |
1 u |
2580 |
| Change |
- 510 |
+ 510 |
|
| After |
1 u + 2070 |
1 u + 510 |
1560 |
Comparing Pamela and
Betty in the end |
7 p |
3 p |
4 p |
Volume of coffee that Pamela had in the end
= 1 u + 2580 - 510
= 1 u + 2070
Difference in the volume of coffee between Pamela and Betty in the end
= 7 p - 3 p
= 4 p
4 p = 2070 - 510
4 p = 1560
1 p = 1560 ÷ 4 = 390
Volume of coffee that Pamela had at first
= 7 p + 510
= 7 x 390 + 510
= 2730 + 510
= 3240 mℓ
Answer(s): 3240 mℓ
