In the seminar room, chairs were arranged in rows of 12. During a workshop, 40 chairs were added to accommodate the number of people. The chairs were rearranged to form rows of 10. As a result, there were 7 more rows.
- How many chairs were there in the extra 7 rows?
- How many chairs were there in the seminar room in the end?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 7 |
Value |
12 |
10 |
Total value |
12 u |
10 u + 70 |
(a)
Number of chairs in the extra 7 rows
= 7 x 10
= 70
(b)
Total number of chairs in the first arrangement
= 1 u x 12
= 12 u
Total number of chairs in the second arrangement
= 10(1 u + 7)
= 10 u + 70
If 40 chairs were included in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
12 u + 40 = 10 u + 70
12 u - 10 u = 70 - 40
2 u = 30
1 u = 30 ÷ 2 = 15
Number of chairs in the seminar room in the end
= 15 x 12 + 40
= 180 + 40
= 220
Answer(s): (a) 70; (b) 220