Question

A celluar phone company offers a contract for which the cost C, in dollars, of t minutes of telephoning is given by C=0.25(t-300)+79.95. Where it is assumed that t_>300 minutes. What times will keep costs between $120.45 and $156.95

Answer 1

you substitute C with the two costs ( 120.45 and 156.95 ) then calculate for t

so you get t=462 minutes for 120.45$
and t= 608 for 156.95 $

do you get it ? :)

Answer 2

Thank you

Answer 3

you're most welcome dude :D