Appendix A - Review - A.8 Problem Solving: Interest, Mixture, Uniform Motion, Constant Rate Job Applications - A.8 Assess Your Understanding - Page A69: 17

$C=150 x, $ where $C$ is the total variable cost, $x$ is the number of dishwashers

Let the total variable cost of manufacturing be $C$ and the number of dishwashers manufactured be $x$. Total variable cost $=150\times $ (number of dishwashers). The mathematical equation is $C=150\times x=150x$