Chapter 2 - Solving Linear Inequalities - 2.2 - Solving Inequalities Using Addition or Subtraction - Exercises - Page 65: 26

$x\geq 5.24$

Let the additional amount that needs to be spend be $x$. Current spending is $\$19.76$. Free service is for at least $\$25$ spending. So the inequality will be: $$19.76+x\geq25$$ $$x\geq25-19.76$$ $$x\geq 5.24$$