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I’M LOSING TIME!!!!!!

you are trying to decide which cell phone plan to purchase. Plan A chargeres $40 for a new phone and $20 a month for usage. Plan B provides the phone for free, but has a fee of $30 a month for usage.
Use the substitution method to determine when the two plans will cost the same.

1 Answer

3 votes

Answer:

Explanation:

Answer:

In 4 months the two plans will cost the same.

Explanation:

Let
m represent the number of months of usage of phone

Let
C represent the total amount charged by the plans.

Plan A:

Plan A charges $40 for a new phone and $20 for per month usage.

Fixed charge = $40

Per month usage charge = $20

Usage charges in dollars for
m months will be =
20x

Thus total charges
C in dollars can be given as:

A)
C=20m+40

Plan B.

Plan B provides the phone for free, but has a fee of $30 for per month usage.

Fixed charge = $0

Per month usage charge = $30

Usage charges in dollars for
m months will be =
30x

Thus total charges
C in dollars can be given as:

B)
C=30m

In order to determine the number of month in which the two plans will charge same we will equate the equations.

Substituting equation B in equation A.


30m=20m+40

Solving for
m

Subtracting both sides by
20m


30m-20m=20m-20m+40


10m=40

Dividing both sides by 10.


(10m)/(10)=(40)/(10)


m=4

Thus, in 4 months Plan A will cost the same as Plan B

User Totte Karlsson
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