Question 83124

Let t= number of units of time needed for the road call

Now we know that it would be more economical to use Rick's if the total cost of the road call is less than Twin City

So our equation to solve is:

50+15t<70+10t  subtract 10t and also 50 from both sides

50-50+15t-10t<70-50+10t-10t  collect like terms

5t<20  divide both sides by 5

t<4 units of time, in other words, if the road call takes less than an hour it would be more economical to use Rick's

Clearly, if t=4 units of time, then the two would cost the same
50+60=70+40
110=110
Hope this helps------ptaylor