Fiona had 90 more buttons than Risa. After Fiona gave away
15 of her buttons and Risa gave away
35 of her buttons, Risa had 86 less buttons than Fiona. How many buttons did Fiona have at first?
| |
Fiona |
Risa |
Comparing Fiona and
Risa at first |
90 more |
|
| Before |
5x1 |
+ 90 |
5x1 |
| Change |
- 1x1 |
- 18 |
- 3x1 |
| After |
4x1 |
+ 72 |
2x1 |
Comparing Fiona and
Risa in the end |
|
86 less |
| |
Fiona |
Risa |
| Before |
5 u + 90 |
5 u |
| Change |
- 1 u - 18 |
- 3 u |
| After |
4 u + 72 |
2 u |
15 x 90 = 18
90 - 18 = 72
Risa had 86 less buttons than Fiona in the end. So, if Risa had another 86 buttons in the end, the number of buttons that Risa and Fiona each had would be the same.
4 u + 72 = 2 u + 86
4 u - 2 u = 86 - 72
2 u = 14
1 u = 14 ÷ 2 = 7
Number of buttons that Fiona had at first
= 5 u + 90
= 5 x 7 + 90
= 35 + 90
= 125
Answer(s): 125
