Some identical novels can be arranged in exactly 10 per row. If the same number of novels is arranged in rows of 7 novels each, there will be 4 more rows but short of 4 novels. How many novels are there altogether?
| |
10 per row |
7 per row |
| Number |
1 u |
1 u + 4 |
| Value |
10 u |
7 |
| Total value |
10 u |
7 u + 28 - 4 |
Number of rows if the novels are arranged in rows of 10 = 1 u
Number of rows if the novels are arranged in rows of 7 = 1 u + 4
Total number of novels if they are arranged in rows of 10
= 10 x 1 u
= 10 u
Total number of novels if they are arranged in rows of 7
= 7 x (1 u + 4) - 4
= 7 u + 28 - 4
= 7 u + 24
The total number of novels remains the same for both cases.
10 u = 7 u + 24
10 u - 7 u = 24
3 u = 24
1 u = 24 ÷ 3 = 8
Total number of novels
= 10 u
= 10 x 8
= 80
Answer(s): 80
