Hilda had 2220 mℓ more coffee than Zoe. After Hilda gave Zoe 470 mℓ of coffee, the ratio of Hilda's coffee to Zoe's coffee became 7 : 3. How much coffee did Hilda have at first? Give your answer in millilitres.
| |
Hilda |
Zoe |
Difference |
| Before |
1 u + 2220 |
1 u |
2220 |
| Change |
- 470 |
+ 470 |
|
| After |
1 u + 1750 |
1 u + 470 |
1280 |
Comparing Hilda and
Zoe in the end |
7 p |
3 p |
4 p |
Volume of coffee that Hilda had in the end
= 1 u + 2220 - 470
= 1 u + 1750
Difference in the volume of coffee between Hilda and Zoe in the end
= 7 p - 3 p
= 4 p
4 p = 1750 - 470
4 p = 1280
1 p = 1280 ÷ 4 = 320
Volume of coffee that Hilda had at first
= 7 p + 470
= 7 x 320 + 470
= 2240 + 470
= 2710 mℓ
Answer(s): 2710 mℓ
