The ratio of Christian's marbles to Grace's marbles at first was 3 : 7. After Christian gave Grace 100 marbles, the ratio of Christian's marbles to Grace's marbles is 1 : 4. What was the number of marbles they had altogether?
| |
Christian |
Grace |
Total |
| Before |
3x5 =
15 u |
7x5 =
35 u
|
10x5 =
50 u |
| Change |
- 100 |
+ 100 |
|
| After |
1x10 =
10 u |
4x10 =
40 u |
5x10 =
50 u |
Number of marbles that Christian gave Grace
= 15 u - 10 u
= 5 u
5 u = 100
1 u = 100 ÷ 5 = 20
Total number of marbles that they had
= 50 u
= 50 x 20
= 1000
Answer(s): 1000
