There were some rows of chairs in a parade square. Each row had 9 chairs. When Anna brought in 2 extra chairs and rearranged all the chairs, there were 5 chairs in each row and 2 more rows than before. How many chairs were there at first?
| |
First
arrangement |
Second
arrangement |
| Number |
1 u |
1 u + 2 |
| Value |
9 |
5 |
| Total value |
9 u |
5 u + 10 |
If another 2 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 + 2 = 5 u + 10
9 u - 5 u = 10 - 2
4 u = 8
1 u = 8 ÷ 4 = 2
Number of chairs at first
= 9 u
= 9 x 2
= 18
Answer(s): 18
