Winnie had thrice the number of rubber blocks as Charlie. Winnie used all her blocks to build 12 identical cars. Charlie used all his blocks to build 5 identical cars. Winnie used 9 more blocks than Charlie for each car. How many blocks did Charlie have?

	Winnie	Charlie
Number	12	5
Value	1 u + 9	1 u
Total value	12 u + 108	5 u

Number of rubber blocks that Charlie used for each car = 1 u
Number of rubber blocks that Winnie used for each car = 1 u + 9

Number of rubber blocks that Charlie had
= 5 x 1 u
= 5 u

Number of rubber blocks that Winnie had
= 12 x (1 u + 9)
= 12 u + 108

Winnie had thrice the number of rubber blocks as Charlie.

3 x 5 u = 12 u + 108
15 u = 12 u + 108
15 u - 12 u = 108
3 u = 108

1 u = 108 ÷ 3 = 36

Number of blocks that Charlie had
= 5 u
= 5 x 36
= 180

Answer(s): 180