Gillian had thrice the number of wooden bricks as Tom. Gillian used all her bricks to build 10 identical cars. Tom used all his bricks to build 4 identical cars. Gillian used 9 more bricks than Tom for each car. How many bricks did Tom have?

	Gillian	Tom
Number	10	4
Value	1 u + 9	1 u
Total value	10 u + 90	4 u

Number of wooden bricks that Tom used for each car = 1 u
Number of wooden bricks that Gillian used for each car = 1 u + 9

Number of wooden bricks that Tom had
= 4 x 1 u
= 4 u

Number of wooden bricks that Gillian had
= 10 x (1 u + 9)
= 10 u + 90

Gillian had thrice the number of wooden bricks as Tom.

3 x 4 u = 10 u + 90
12 u = 10 u + 90
12 u - 10 u = 90
2 u = 90

1 u = 90 ÷ 2 = 45

Number of bricks that Tom had
= 4 u
= 4 x 45
= 180

Answer(s): 180