Equations and Inequalities

Solving a decimal word problem using a linear equation with the variable...

Customers of a phone company can choose between two service plans for long distance calls. The first plan has no monthly fee but charges $$0\mathrm{.}11$ for each minute of calls. The second plan has a $$21$ monthly fee and charges an additional $$0\mathrm{.}07$ for each minute of calls. For how many minutes of calls will the costs of the two plans be equal?