Cindy had 2130 mℓ more coffee than Lynn. After Cindy gave Lynn 570 mℓ of coffee, the ratio of Cindy's coffee to Lynn's coffee became 7 : 4. How much coffee did Cindy have at first? Give your answer in millilitres.
| |
Cindy |
Lynn |
Difference |
| Before |
1 u + 2130 |
1 u |
2130 |
| Change |
- 570 |
+ 570 |
|
| After |
1 u + 1560 |
1 u + 570 |
990 |
Comparing Cindy and
Lynn in the end |
7 p |
4 p |
3 p |
Volume of coffee that Cindy had in the end
= 1 u + 2130 - 570
= 1 u + 1560
Difference in the volume of coffee between Cindy and Lynn in the end
= 7 p - 4 p
= 3 p
3 p = 1560 - 570
3 p = 990
1 p = 990 ÷ 3 = 330
Volume of coffee that Cindy had at first
= 7 p + 570
= 7 x 330 + 570
= 2310 + 570
= 2880 mℓ
Answer(s): 2880 mℓ
