Some identical story books can be arranged in exactly 15 per row. If the same number of story books is arranged in rows of 9 story books each, there will be 5 more rows and 3 story books left over. How many story books are there altogether?
| |
15 per row |
9 per row |
| Number |
1 u |
1 u + 5 |
| Value |
15 |
9 |
| Total value |
15 u |
9 u + 45 + 3 |
Number of rows if the story books are arranged in rows of 15 = 1 u
Number of rows if the story books are arranged in rows of 9 = 1 u + 5
Total number of story books if they are arranged in rows of 15
= 15 x 1 u
= 15 u
Total number of story books if they are arranged in rows of 9
= 9 x (1 u + 5) + 3
= 9 u + 45 + 3
= 9 u + 48
The total number of story books remains the same for both cases.
15 u = 9 u + 48
15 u - 9 u = 48
6 u = 48
1 u = 48 ÷ 6 = 8
Total number of story books
= 15 u
= 15 x 8
= 120
Answer(s): 120
