Chapter 3 - Equations and Problem Solving - 3.2 - Equations and Problem Solving - Problem Set 3.2 - Page 106: 52

$x=11$

$\text{Let}$ $x$ $\text{represent the certain number.}$ Since $14$ is added to this number, we write $14+x$. Since that sum is $25$, we write that it is equal to $25$ . When we combine these two statements, we get the equation $14+x=25$. To solve this equation for $x$, we must subtract $14$ from both sides: $$14-14+x=25-14$$$$x=11$$