a cellular company offers a contract for which the cost c in dollars of t minutes of telephoning is given by c=0.25(t-600)+57.95 where it is assumed that t than 600 mins. what times will keep the costs between 98.45 and 141.70

Question

a cellular company offers a contract for which the cost c in dollars of t  minutes of telephoning is given by c=0.25(t-600)+57.95 where it is assumed that t > than 600 mins. what times will keep the costs between 98.45 and 141.70

dumbcow · Answer

$$98.45 <.25(t-600)+57.95 < 141.70$$

dumbcow · Answer

subtract 57.95 on both sides
$$40.5<.25(t-600) <83.75$$
multiply by 4 on both sides
$$162<t-600<335$$
add 600 on both sides
$$762 < t <935$$