# math

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A cell phone company offers a contract for which the cost C, in dollars, of T minutes of telephoning is given by C=0.25(t-600)+71.95, where it is assumed the t greater than 600 minutes. What times will keep costs between \$119.20 and \$135.45?

• math -

\$119.20 = 0.25(t-600) + 71.95

\$135.45 = 0.25(t-600) + 71.95

Get rid of parenthesis and subtract 71.65 form both sides.

47.25 = .25t - 150

197.25 = .25t

Multiply both sides by 4.

789 = t

Do the same for the second equation.

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