There were some rows of chairs in a hall. Each row had 9 chairs. When Jade brought in 21 extra chairs and rearranged all the chairs, there were 6 chairs in each row and 5 more rows than before. How many chairs were there at first?
|
First arrangement |
Second arrangement |
Number |
1 u |
1 u + 5 |
Value |
9 |
6 |
Total value |
9 u |
6 u + 30 |
If another 21 chairs are added in the first arrangement, the total number of chairs in the first arrangement and the second arrangement will be the same.
9 u + 21 = 6 u + 30
9 u - 6 u = 30 - 21
3 u = 9
1 u = 9 ÷ 3 = 3
Number of chairs at first
= 9 u
= 9 x 3
= 27
Answer(s): 27