Question

For his phone service, Chris pays a monthly fee of
$19, and he pays an additional $0.04 per minute of use. The least he has been charged in a month is $78.16. What are the possible numbers of minutes he has used his phone in a month? Use m for the number of minutes, and solve your inequality for m.

Answer 1

A

Answer 2

So, we first have to set up an equation.
\[y=???? + 19\]

Now, for example. Let's say I made 10 dollars an hour and wanted to know how many dollars I would make in 2 hours. It would be 20. Would I multiply, add, subtract, or divide 10 and 2 to get 20?

Answer 3

mult @FortyTheRapper

Answer 4

Alright, so we have

\[y = 0.04x + 19\]

We have an unknown Y(total) and an unknown X(minutes). They actually gave us the total, do you see that?

Answer 5

yes

Answer 6

What is it?

Answer 7

20?

Answer 8

It's the least he's been charged a month, which is 78.16. With that, we can complete the equation

\[0.04m+19 = 78.16\]

Now, the last thing we have to do is solve for m, and we can find out the max possible number of minutes he has used in a month

Answer 9

oh ok

Answer 10

Let's move the 19 first. What would you do?

Answer 11

subtract it by the 78.16? right?

Answer 12

Yep!
\[0.04m +19-(19)= 78.16 - 19\]

To get us

\[0.04m = 59.16\]

Now the last step is to get the 0.04 away from the m. Any idea

Answer 13

umm divide?

Answer 14

Right

\[m = \frac{ 59.16 }{ 0.04}\]

Now we just put that in the calculator and there's our answer

Answer 15

1,479

Answer 16

Yes, 1,479 minutes. Good job

Answer 17

do i turn it into an equation now? cause it says in the end of the problem, use m for the number of minutes, and solve your inequality for m

Answer 18

Nah, those were just instructions on how to do this problem.

"What are the possible numbers of minutes he has used his phone in a month" was the question

I guess you can say "Between 0 and 1,479 minutes" if you wanted