Cindy had 1840 mℓ more coffee than Wendy. After Cindy gave Wendy 520 mℓ of coffee, the ratio of Cindy's coffee to Wendy's coffee became 7 : 3. How much coffee did Cindy have at first? Give your answer in millilitres.
|
Cindy |
Wendy |
Difference |
Before |
1 u + 1840 |
1 u |
1840 |
Change |
- 520 |
+ 520 |
|
After |
1 u + 1320 |
1 u + 520 |
800 |
Comparing Cindy and Wendy in the end |
7 p |
3 p |
4 p |
Volume of coffee that Cindy had in the end
= 1 u + 1840 - 520
= 1 u + 1320
Difference in the volume of coffee between Cindy and Wendy in the end
= 7 p - 3 p
= 4 p
4 p = 1320 - 520
4 p = 800
1 p = 800 ÷ 4 = 200
Volume of coffee that Cindy had at first
= 7 p + 520
= 7 x 200 + 520
= 1400 + 520
= 1920 mℓ
Answer(s): 1920 mℓ