Long Distance Phone Calls (Word Problem) Help?

Question

The weekday rate for a telephone call is $0.75 for the first minute and plus $0.55 for each additional minute. Determine the length of the call that costs $5.15. What would have been the cost of the call if it had been made during the weekend when there is a 60% discount?

I figured out the first part of the problem, which is 9 minutes. I just need help setting up and figuring out the cost of the call during the weekend when there was a 60% discount. Thanks!

Answer 1

Hayley,

 

I set up the function as Cost=0.55(x-1)+0.75   [the 0.55 rate is for all minutes except the first, so x-1, the 0.75 is the fixed cost for the first minute.]

 

So,  5.15=0.55(x-1)+.75

5.15=0.55x-0.55+0.75

5.15=0.55x+0.20

4.95=0.55x

9=x

 

Substitute 9 for x in the original function and you get 5.15=0.55(9-1)+0.75 which does equal.

 

I hope that helped.