Appendix - Extra Word Problems - Page 523: 5

2

We denote the unknown number as $x$. Therefore, six times the unknown number is $6x$. We are told that $6x$ is subtracted from 15, so we obtain: $15-6x=3$ Now solving the above equation, we find: Step 1: $15-6x=3$ Step 2: $-6x=3-15$ Step 3: $-6x=-12$ Step 4: $x=\frac{-12}{-6}$ Step 5: $x=2$ Therefore, the unknown number is $2$.