Erika had 90% as many sweets as Xuan. Erika gave away 10% of her sweets and Xuan bought another 110 sweets. As a result, Erika now has 70% as many sweets as Xuan. Find the number of sweets that Xuan had at first.
| |
Erika |
Xuan |
| Before |
9x7 |
10x7 |
| Change |
- 0.9x7 |
+ 110 |
| After |
8.1x7 |
10x7 + 110 |
Comparing Erika and
Xuan in the end |
7x8.1 |
10x8.1 |
| |
Erika |
Xuan |
| Before |
63 u |
70 u |
| Change |
- 6.3 u |
+ 110 |
After
|
56.7 u
|
70 u + 110 =
81 u |
90% =
90100 =
91010% x 9
=
10100 x 9
= 0.9
70% =
70100 =
710The number of sweets that Erika had in the end is repeated.
Make the number of sweets that Erika had in the end the same.
The number of sweets that Xuan had in the end is repeated.
70 u + 110 = 81 u
81 u - 70 u = 110
11 u = 110
1 u = 110 ÷ 11 = 10
Number of sweets that Xuan had at first
= 70 u
= 70 x 10
= 700
Answer: 700
