In the seminar room, chairs were arranged in rows of 18. During a workshop, 12 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 15. As a result, there were 3 more rows.
- How many chairs were there in the extra 3 rows?
- How many chairs were there in the seminar room in the end?
| |
First
arrangement |
Second
arrangement |
| Number |
1 u |
1 u + 3 |
| Value |
18 |
15 |
| Total value |
18 u |
15 u + 45 |
(a)
Number of chairs in the extra 3 rows
= 3 x 15
= 45
(b)
Total number of chairs in the first arrangement
= 1 u x 18
= 18 u
Total number of chairs in the second arrangement
= 15(1 u + 3)
= 15 u + 45
If 12 chairs were included in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
18 u + 12 = 15 u + 45
18 u - 15 u = 45 - 12
3 u = 33
1 u = 33 ÷ 3 = 11
Number of chairs in the seminar room in the end
= 11 x 18 + 12
= 198 + 12
= 210
Answer(s): (a) 45; (b) 210
