23 of Betty's money was equal to
12 of Risa's money at first. After Betty spent $33 and Risa spent
25 of her money, Betty had
13 as much money as Risa.
- How much money did Risa have at first?
- How much money did Risa have in the end?
| |
Betty |
Risa |
Comparing Betty
and Risa at first |
3x5 =
15 u |
4x5 =
20 u |
| Before |
|
5x4 =
20 u |
| Change |
- $33 |
- 2x4 =
- 8 u |
| After |
|
3x4 =
12 u |
Comparing Betty
and Risa in the end |
1x4 =
4 u |
3x4 =
12 u |
23 Betty's money =
12 Risa's money
Make numerators the same.
23 Betty's money =
1x22x2 Risa's money
23 Betty's money =
24 Risa's money
Betty's money : Risa's money = 3 : 4
The amount that Risa had at first is repeated. Make the amount that Risa had at first the same. LCM of 4 and 5 is 20.
Amount that Betty spent
= 15 u - 4 u
= 11 u
11 u = 33
1 u = 33 ÷ 11 = 3
(a)
Amount that Risa had at first
= 20 u
= 20 x 3
= $60
(b)
Amount that Risa had in the end
= 12 u
= 12 x 3
= $36
Answer(s): (a) $60; (b) $36
