Opal had 90% as many sweets as Ivory. Opal gave away 20% of her sweets and Ivory bought another 20 sweets. As a result, Opal now has 70% as many sweets as Ivory. Find the number of sweets that Ivory had at first.
| |
Opal |
Ivory |
| Before |
9x7 |
10x7 |
| Change |
- 1.8x7 |
+ 20 |
| After |
7.2x7 |
10x7 + 20 |
Comparing Opal and
Ivory in the end |
7x7.2 |
10x7.2 |
| |
Opal |
Ivory |
| Before |
63 u |
70 u |
| Change |
- 12.6 u |
+ 20 |
After
|
50.4 u
|
70 u + 20 =
72 u |
90% =
90100 =
91020% x 9
=
20100 x 9
= 1.8
70% =
70100 =
710The number of sweets that Opal had in the end is repeated.
Make the number of sweets that Opal had in the end the same.
The number of sweets that Ivory had in the end is repeated.
70 u + 20 = 72 u
72 u - 70 u = 20
2 u = 20
1 u = 20 ÷ 2 = 10
Number of sweets that Ivory had at first
= 70 u
= 70 x 10
= 700
Answer: 700
