Opal had 90% as many lollipops as Betty. Opal gave away 10% of her lollipops and Betty bought another 220 lollipops. As a result, Opal now has 70% as many lollipops as Betty. Find the number of lollipops that Betty had at first.
| |
Opal |
Betty |
| Before |
9x7 |
10x7 |
| Change |
- 0.9x7 |
+ 220 |
| After |
8.1x7 |
10x7 + 220 |
Comparing Opal and
Betty in the end |
7x8.1 |
10x8.1 |
| |
Opal |
Betty |
| Before |
63 u |
70 u |
| Change |
- 6.3 u |
+ 220 |
After
|
56.7 u
|
70 u + 220 =
81 u |
90% =
90100 =
91010% x 9
=
10100 x 9
= 0.9
70% =
70100 =
710The number of lollipops that Opal had in the end is repeated.
Make the number of lollipops that Opal had in the end the same.
The number of lollipops that Betty had in the end is repeated.
70 u + 220 = 81 u
81 u - 70 u = 220
11 u = 220
1 u = 220 ÷ 11 = 20
Number of lollipops that Betty had at first
= 70 u
= 70 x 20
= 1400
Answer: 1400
