Min had 90% as many lollipops as Mary. Min gave away 20% of her lollipops and Mary bought another 30 lollipops. As a result, Min now has 70% as many lollipops as Mary. Find the number of lollipops that Mary had at first.
| |
Min |
Mary |
| Before |
9x7 |
10x7 |
| Change |
- 1.8x7 |
+ 30 |
| After |
7.2x7 |
10x7 + 30 |
Comparing Min and
Mary in the end |
7x7.2 |
10x7.2 |
| |
Min |
Mary |
| 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 lollipops that Min had in the end is repeated.
Make the number of lollipops that Min had in the end the same.
The number of lollipops that Mary 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 lollipops that Mary had at first
= 70 u
= 70 x 15
= 1050
Answer: 1050
