Zoe had 90% as many chocolate bars as Diana. Zoe gave away 20% of her chocolate bars and Diana bought another 10 chocolate bars. As a result, Zoe now has 70% as many chocolate bars as Diana. Find the number of chocolate bars that Diana had at first.
| |
Zoe |
Diana |
| Before |
9x7 |
10x7 |
| Change |
- 1.8x7 |
+ 10 |
| After |
7.2x7 |
10x7 + 10 |
Comparing Zoe and
Diana in the end |
7x7.2 |
10x7.2 |
| |
Zoe |
Diana |
| Before |
63 u |
70 u |
| Change |
- 12.6 u |
+ 10 |
After
|
50.4 u
|
70 u + 10 =
72 u |
90% =
90100 =
91020% x 9
=
20100 x 9
= 1.8
70% =
70100 =
710The number of chocolate bars that Zoe had in the end is repeated.
Make the number of chocolate bars that Zoe had in the end the same.
The number of chocolate bars that Diana had in the end is repeated.
70 u + 10 = 72 u
72 u - 70 u = 10
2 u = 10
1 u = 10 ÷ 2 = 5
Number of chocolate bars that Diana had at first
= 70 u
= 70 x 5
= 350
Answer: 350
