Algebra word problem

Question

Cell phone company A charges .25 a minute. Cell phone company B charges a $20 monthly fee and .05 a minute. At what number of minutes, will it cost the same at both companies?

Answer 1

Let x = the number of cell phone minutes used per month

 

The monthly cost for using company A is:

 

Cost_A = ($0.25)x             [$0.25 per minute times x minutes]

 

The monthly cost of using company B is:

 

Cost_B = ($0.05)x  + $20       [$0.05 per minute times x minutes plus a $20 monthly fee]

 

Set them equal and solve for x:

 

Cost_A = Cost_B

 

($0.25)x = ($0.05)x + $20

($0.20)x = $20

x = $20/($0.20)

 

x = 100 minutes

 

Below 100 minutes, company A is cheaper.  Above 100 minutes, company B is cheaper.