Risa had 120 more buttons than Kathy. After Risa gave away
15 of her buttons and Kathy gave away
34 of her buttons, Kathy had 151 less buttons than Risa. How many buttons did Risa have at first?
| |
Risa |
Kathy |
Comparing Risa and
Kathy at first |
120 more |
|
| Before |
5x4 |
+ 120 |
4x5 |
| Change |
- 1x4 |
- 24 |
- 3x5 |
| After |
4x4 |
+ 96 |
1x5 |
Comparing Risa and
Kathy in the end |
|
151 less |
| |
Risa |
Kathy |
| Before |
20 u + 120 |
20 u |
| Change |
- 4 u - 24 |
- 15 u |
| After |
16 u + 96 |
5 u |
15 x 120 = 24
120 - 24 = 96
Kathy had 151 less buttons than Risa in the end. So, if Kathy had another 151 buttons in the end, the number of buttons that Kathy and Risa each had would be the same.
16 u + 96 = 5 u + 151
16 u - 5 u = 151 - 96
11 u = 55
1 u = 55 ÷ 11 = 5
Number of buttons that Risa had at first
= 20 u + 120
= 20 x 5 + 120
= 100 + 120
= 220
Answer(s): 220
