$c = 5(n + 1)$
Work Step by Step
The first figure has 10 circles. The second has 15. The third has 20, and so on. It is clear each figure has five circles more than the previous figure. If we divide the number of circles in each figure by 5, we get 2, 3, 4, 5 in that order. The input for each figure is 1, 2, 3, 4. These values are one less than the number of circles divided by 5, respectively. Therefore, n (the input) increased by 1 and multiplied by 5 is the number of circles (the output). The process column shows this for each input and output.