The relationship between the number of toy cars and the cost of cars expressed in the given data. The following is the pattern that can be formed from the given data. It is as follows :
2 × 1 + 1 = 3
4 × 1 + 2 = 6
6 × 1 + 3 = 9
8 × 1 + 4 = 12
10 × 1 + 5 = 15
12 × 1 + 6 = 18
14 × 1 + 7 = 21
16 × 1 + 8 = 24
18 × 1 + 9 = 27
So, the cost of 18 toy cars is 27 dollars. Hence, this is the required solution.
