Cindy had 90% as many chocolate bars as Jean. Cindy gave away 20% of her chocolate bars and Jean bought another 20 chocolate bars. As a result, Cindy now has 70% as many chocolate bars as Jean. Find the number of chocolate bars that Jean had at first.
| |
Cindy |
Jean |
| Before |
9x7 |
10x7 |
| Change |
- 1.8x7 |
+ 20 |
| After |
7.2x7 |
10x7 + 20 |
Comparing Cindy and
Jean in the end |
7x7.2 |
10x7.2 |
| |
Cindy |
Jean |
| Before |
63 u |
70 u |
| Change |
- 12.6 u |
+ 20 |
After
|
50.4 u
|
70 u + 20 =
72 u |
90% =
90100 =
91020% x 9
=
20100 x 9
= 1.8
70% =
70100 =
710The number of chocolate bars that Cindy had in the end is repeated.
Make the number of chocolate bars that Cindy had in the end the same.
The number of chocolate bars that Jean had in the end is repeated.
70 u + 20 = 72 u
72 u - 70 u = 20
2 u = 20
1 u = 20 ÷ 2 = 10
Number of chocolate bars that Jean had at first
= 70 u
= 70 x 10
= 700
Answer: 700
