PSLE
In a school hall, chairs were arranged in rows such that there were exactly 19 chairs in each row. For a concert, Simon brought 8 more chairs into the school hall and rearranged all the chairs. There are now exactly 8 chairs in each row and 12 more rows than before. How many chairs are there in the school hall for the concert in the end?

	Before	After
Number	1 u	1 u + 12
Value	19	8
Total value	19 u + 8	8 u + 96

Number of rows at first = 1 u
Number of rows in the end = 1 u + 12

Number of chairs at first after the 8 chairs were brought in
= 19 x 1 u + 8
= 19 u + 8

Number of chairs in the end
= 8 x (1 u + 12)
= 8 u + 96

The total number of chairs is equal.

19 u + 8 = 8 u + 96
19 u - 8 u = 96 - 8 
11 u = 88

1 u = 88 ÷ 11 = 8 

Number of chairs in the end
= 8 u + 96
= 8 x 8 + 96
= 160

Answer(s): 160