Chapter 1 - Expressions, Equations, and Inequalities - 1-1 Patterns and Expressions - Practice and Problem-Solving Exercises - Page 7: 13

$t = 2n$

The first figure has 2 tiles. The second has 4. The third has 6, and so on. It is clear each figure has two tiles more than the previous figure. Therefore, as n (the input) gets bigger by 1, the number of tiles (the output) gets bigger by 2. 2 is 2 x 1. 4 is 2 x 2, etc. So, 2 x n (the input) gives you the number of tiles (the output). The process column shows this for each input and output.