Question

Phone plan A charges $1.25 for the first minute and $0.15 for every minute thereafter. Phone plan B charges a $0.90 connection fee and $0.20 per minute. Which of the following equations could be used to find the length, in minutes, of a phone call that costs the same under either plan?

(A) 1.25 + 0.15x = 0.90x + 0.20
(B) 1.25 + 0.15x = 0.90 + 0.20x
(C) 1.25 + 0.15(x – 1) = 0.90 + 0.20x
(D) 1.25 + 0.15(x – 1) = 0.90 + 0.20(x – 1)
(E) 1.25 + 0.15x + 0.90x + 0.20 = x

Answer 1

The answer is (C)
`1.25+0.15(x-1)=0.90+0.20x`.

Explanation:

Now, to find the equation for finding the length, in minutes, of a phone call that costs the same under either plan.

Let the phone charges per minute be
`x.`

So, to get the equation of the phone plan A as the phone plan A charges $1.25 for the first minute and after that $0.15 for every minute:

`1.25+0.15x-0.15`

`=1.25-0.15(x-1)`

Now, to get the equation of the phone plan B as given phone plan B charges a $0.90 connection fee and $0.20 per minute:

`0.90+0.20x`

As, the phone call that costs the same under either plan.

Thus:

`1.25+0.15(x-1)=0.90+0.20x`

Therefore, the answer is (C)
`1.25+0.15(x-1)=0.90+0.20x`.