Question

How would this word problem be solved?

A phone call costs $0.58 per minute for the first three minutes and $0.15 per minute for each additional minute. If the total charge for the call was $4.29, how many minutes long was the call?

Answer 1

20 minutes
0.58x3=1.74
0.15x17=2.55
2.55+1.74=4.29

Answer 2

31 minutes in total

Explanation:

Going step by step, where m = minutes after the first 3:

0.58 + 0.15m = 4.78

We want to solve for m, so we need to isolate it. The first step is to get rid of 0.58 to simplify our equation.

0.15m = 4.78 - 0.58

Now we have:

0.15m = 4.20

To isolate further, we need to remove 0.15.

m = 4.20 / 0.15

m = 28

Now, we add the first 3 minutes to m to get our total time.

28 + 3 = 31