Opal had 1920 mℓ more coffee than Yoko. After Opal gave Yoko 480 mℓ of coffee, the ratio of Opal's coffee to Yoko's coffee became 7 : 4. How much coffee did Opal have at first? Give your answer in millilitres.
| |
Opal |
Yoko |
Difference |
| Before |
1 u + 1920 |
1 u |
1920 |
| Change |
- 480 |
+ 480 |
|
| After |
1 u + 1440 |
1 u + 480 |
960 |
Comparing Opal and
Yoko in the end |
7 p |
4 p |
3 p |
Volume of coffee that Opal had in the end
= 1 u + 1920 - 480
= 1 u + 1440
Difference in the volume of coffee between Opal and Yoko in the end
= 7 p - 4 p
= 3 p
3 p = 1440 - 480
3 p = 960
1 p = 960 ÷ 3 = 320
Volume of coffee that Opal had at first
= 7 p + 480
= 7 x 320 + 480
= 2240 + 480
= 2720 mℓ
Answer(s): 2720 mℓ
