Kathy had 90% as many sweets as Yoko. Kathy gave away 10% of her sweets and Yoko bought another 210 sweets. As a result, Kathy now has 60% as many sweets as Yoko. Find the number of sweets that Kathy had in the end.
| |
Kathy |
Yoko |
| Before |
9x3 |
10x3 |
| Change |
- 0.9x3 |
+ 210 |
| After |
8.1x3 |
10x3 + 210 |
Comparing Kathy and
Yoko in the end |
3x8.1 |
5x8.1 |
| |
Kathy |
Yoko |
| Before |
27 u |
30 u |
| Change |
- 2.7 u |
+ 210 |
After
|
24.3 u
|
30 u + 210 =
40.5 u |
90% =
90100 =
91010% x 9
=
10100 x 9
= 0.9
60% =
60100 =
35The number of sweets that Kathy had in the end is repeated.
Make the number of sweets that Kathy had in the end the same.
The number of sweets that Yoko had in the end is repeated.
30 u + 210 = 40.5 u
40.5 u - 30 u = 210
10.5 u = 210
1 u = 210 ÷ 10.5 = 20
Number of sweets that Kathy had in the end
= 24.3 u
= 24.3 x 20
= 486
Answer: 486
