Diana and Barbara collected buttons. Barbara gave 70% of her buttons to Diana. As a result, Diana's buttons increased by 20%. If Diana had 504 buttons left, find the total number of buttons the two girls had at first.
| |
Comparing the change
in Barbara's buttons |
Barbara |
Diana |
| Before |
10x1 =
10 u |
|
5x7 =
35 u |
| Change |
- 7x1 =
- 7 u |
- 1x7 =
- 7 u |
+ 1x7 =
+ 7 u |
| After |
3x1 =
3 u |
|
6x7 =
42 u |
70% =
70100 =
710 20% =
20100 =
15 The number of buttons that Diana gave to Barbara is repeated. Make the number of buttons that Diana gave to Barbara the same. LCM of 1 and 7 is 7.
Number of buttons that Diana had in the end = 42 u
42 u = 504
1 u = 504 ÷ 42 = 12
Number of buttons that Barbara and Diana had at first
= 10 u + 35 u
= 45 u
= 45 x 12
= 540
Answer(s): 540
