SOLUTION: I need help to assist my 7th grader. How to set up ratio.... Phone Plan 1 is $.18 per minute Phone Plan 2 is $50 base plan and $.10 per minute. At what point is it cheape

Algebra ->  Equations -> SOLUTION: I need help to assist my 7th grader. How to set up ratio.... Phone Plan 1 is $.18 per minute Phone Plan 2 is $50 base plan and $.10 per minute. At what point is it cheape      Log On


   

Question 357055: I need help to assist my 7th grader.
How to set up ratio....
Phone Plan 1 is $.18 per minute
Phone Plan 2 is $50 base plan and $.10 per minute.
At what point is it cheaper to use plan 1?
How do I show her how to do this?
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Let m = minutes used
.
Phone Plan 1 is $.18 per minute
cost of plan 1 = .18m
.
Phone Plan 2 is $50 base plan and $.10 per minute.
cost of plan 2 = .10m + 50
.
At what point is it cheaper to use plan 1?
"cost of plan 1" < "cost of plan 2"
.18m < .10m + 50
subtracting .10m from both sides:
.08m < 50
dividing both sides by .08
m < 50/.08
m < 625 minutes
.
Therefore:
At what point is it cheaper to use plan 1?
when minutes used is less than 625 minutes