Glen, Peter and Fred had 370 marbles. After Glen used 18 marbles and Peter used
38 of her marbles, Glen had four times as many marbles left as Peter. Fred bought another 28 marbles, he had twice the number of marbles Peter had left. How many marbles did Fred have at first?
| |
Glen |
Peter |
Fred |
Total |
| Before |
20 u + 18 |
8 u |
10 u - 28 |
370 |
| Change |
- 18 |
- 3 u |
+ 28 |
|
| After |
20 u |
5 u |
10 u |
|
Comparing Glen
and Peter in the end |
4 |
1 |
|
|
Comparing Fred
and Peter in the end |
|
1 |
2 |
|
Number of marbles that Glen had in the end
= 4 x 5 u
= 20 u
Number of marbles that Fred had in the end
= 2 x 5 u
= 10 u
Total number of marbles at first
= 20 u + 18 + 8 u + 10 u - 28
= 38 u - 10
38 u - 10 = 370
38 u = 370 + 10
38 u = 380
1 u = 380 ÷ 38 = 10
Number of marbles that Fred had at first
= 10 u - 28
= 10 x 10 - 28
= 100 - 28
= 72
Answer(s): 72
