Some identical story books can be arranged in exactly 11 per row. If the same number of story books is arranged in rows of 7 story books each, there will be 6 more rows but short of 2 story books. How many story books are there altogether?
| |
11 per row |
7 per row |
| Number |
1 u |
1 u + 6 |
| Value |
11 u |
7 |
| Total value |
11 u |
7 u + 42 - 2 |
Number of rows if the story books are arranged in rows of 11 = 1 u
Number of rows if the story books are arranged in rows of 7 = 1 u + 6
Total number of story books if they are arranged in rows of 11
= 11 x 1 u
= 11 u
Total number of story books if they are arranged in rows of 7
= 7 x (1 u + 6) - 2
= 7 u + 42 - 2
= 7 u + 40
The total number of story books remains the same for both cases.
11 u = 7 u + 40
11 u - 7 u = 40
4 u = 40
1 u = 40 ÷ 4 = 10
Total number of story books
= 11 u
= 11 x 10
= 110
Answer(s): 110
