Expert: Steve Holleran - 3/30/2008

Question
Hello, i am doing a project in math but im kind of stumped, we have word problems over functions, i am to figure out the follow answers for this sentence (The total charge is the sum of the basic $35 Charge plus $.45 for each minute you talk over the first 300 minutes) the questions are how is the total charge computed?(witch is 35+(x-300+.45) and decide the letter for the main function which is(X) and these to im stuck on, define the function rule: and Evaluate the function for 320 minutes?? if U could help i would be greatly thankful! Thanks

Answer
Hi John,

I think you just have a small typo in your formula.  Otherwise, you've got it.

I think the equation for the total charge should be:

    T = $35 + .45(x - 300)   where x is the number of minutes.

For the function rule, I would just expand and simplify:

    T = 35 + .45x - 135

    T = .45x - 100

Then T(320) = .45(320) - 100 =  $44.00


I hope that's what you needed.

Steve