Anna’s cell phone plan charges her $30 per month plus a $150 one-time activation fee. Evelyn’s cell phone plan charges her $20 per month, plus a $450 one-time activation fee. After how many months are the costs for the girls’ cell phone plans the same?

Given:

Anna’s cell phone plan charges her $30 per month plus a $150 one-time activation fee.

Evelyn’s cell phone plan charges her $20 per month, plus a $450 one-time activation fee.

To find:

The number of months after which the costs for the girls’ cell phone plans the same.

Solution:

Let x be the number of months.

Total cost = Fixed cost + Variable cost

According to the question, cost equation for Anna’s cell phone is

          ...(i)

Cost equation for Evelyn's cell phone is

        ...(ii)

Equate (i) and (ii) to find the time after which the costs for the girls’ cell phone plans the same.

Divide both sides by 10.

Therefore, the costs for the girls’ cell phone plans the same after 10 months.

isi

step-by-step explanation:

use that smart brain

i think it is everything has to equal 180 so, if i correct 4=c. 6=d. 8=a. 7=b. and the last question would be c. because they are parallel lines and they are congruent.

step-by-step explanation:

the reason everything has to equal to 180 is because that is how it works. i'm guessing that is its rule. 4 and 8 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 6 and 7 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 60+60 is 180. so, now you have your answer