Penelope had 90% as many chocolate bars as Hilda. Penelope gave away 20% of her chocolate bars and Hilda bought another 30 chocolate bars. As a result, Penelope now has 70% as many chocolate bars as Hilda. Find the number of chocolate bars that Hilda had at first.
| |
Penelope |
Hilda |
| Before |
9x7 |
10x7 |
| Change |
- 1.8x7 |
+ 30 |
| After |
7.2x7 |
10x7 + 30 |
Comparing Penelope and
Hilda in the end |
7x7.2 |
10x7.2 |
| |
Penelope |
Hilda |
| Before |
63 u |
70 u |
| Change |
- 12.6 u |
+ 30 |
After
|
50.4 u
|
70 u + 30 =
72 u |
90% =
90100 =
91020% x 9
=
20100 x 9
= 1.8
70% =
70100 =
710The number of chocolate bars that Penelope had in the end is repeated.
Make the number of chocolate bars that Penelope had in the end the same.
The number of chocolate bars that Hilda had in the end is repeated.
70 u + 30 = 72 u
72 u - 70 u = 30
2 u = 30
1 u = 30 ÷ 2 = 15
Number of chocolate bars that Hilda had at first
= 70 u
= 70 x 15
= 1050
Answer: 1050
