Risa had $90 less than Barbara. Barbara spent
27 of her money and Risa spent
23 of her money. In the end, Barbara had 3 times as much as Risa. Find the amount of money Barbara had at first.
| |
Barbara |
Risa |
Comparing Barbara
and Risa at first |
$90 more |
|
| Before |
7x3 =
21 u |
3x5 =
15 u |
| Change |
- 2x3 =
- 6 u |
- 2x5 =
- 10 u |
| After |
5x3 =
15 u |
1x5 =
5 u |
Comparing Barbara
and Risa in the end |
3x5 =
15 u |
1x5 =
5 u |
The amount that Barbara had in the end is repeated. Make the amount that Barbara had in the end the same. LCM of 3 and 5 is 15.
Amount that Risa had less than Barbara
= 21 u - 15 u
= 6 u
6 u = 90
1 u = 90 ÷ 6 = 15
Amount that Barbara had at first
= 21 u
= 21 x 15
= $315
Answer(s): $315
