In the school hall, chairs were arranged in rows of 18. During a function, 15 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 school hall 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 15 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 + 15 = 15 u + 45
18 u - 15 u = 45 - 15
3 u = 30
1 u = 30 ÷ 3 = 10
Number of chairs in the school hall in the end
= 10 x 18 + 15
= 180 + 15
= 195
Answer(s): (a) 45; (b) 195