Joelle had 33 more marbles than Risa. After Risa gave away
15 of her marbles, Joelle had twice as many marbles as Risa. How many marbles did Risa have at first?
| |
Joelle |
Risa |
Comparing Joelle and
Risa at first |
33 more |
|
| Before |
8 u |
5 u |
| Change |
|
- 1 u |
| After |
8 u |
4 u |
Comparing Joelle and
Risa in the end |
2x4 =
8 u |
1x4 =
4 u |
Number of marbles that Risa had in the end is repeated. Make the number of marbles that Risa had in the end the same. LCM of 1 and 4 is 4.
Number of marbles that Joelle had at first = 8 u
Number of marbles that Joelle had more than Risa at first
= 8 u - 5 u
= 3 u
3 u = 33
1 u = 33 ÷ 3 = 11
Number of marbles that Risa had at first
= 5 u
= 5 x 11
= 55
Answer(s): 55
