The phone company charges Rachel 12 cents per minute for her long distance calls. A discount company called Rachel and offered her long distance service for 1/2 cent per minute, but will charge a $46 monthly fee. How many minutes per month must Rachel talk on the phone to make the discount a better deal?
Minutes Rachel talks = m
Current plan cost = 0.12m
New plan cost = 0.005m + 46
Set new plan equal to current plan:
0.005m + 46 = 0.12m
Solve for m in the equation 0.005m + 46 = 0.12m
Step 1: Group variables:
We need to group our variables 0.005m and 0.12m. To do that, we subtract 0.12m from both sides
0.005m + 46 - 0.12m = 0.12m - 0.12m
Step 2: Cancel 0.12m on the right side:
-0.115m + 46 = 0
Step 3: Group constants:
We need to group our constants 46 and 0. To do that, we subtract 46 from both sides
-0.115m + 46 - 46 = 0 - 46
Step 4: Cancel 46 on the left side:
-0.115m = -46
Step 5: Divide each side of the equation by -0.115
-0.115m/-0.115 = -46/-0.115
m = 400
She must talk over 400 minutes for the new plan to be a better deal
Source
Minutes Rachel talks = m
Current plan cost = 0.12m
New plan cost = 0.005m + 46
Set new plan equal to current plan:
0.005m + 46 = 0.12m
Solve for m in the equation 0.005m + 46 = 0.12m
Step 1: Group variables:
We need to group our variables 0.005m and 0.12m. To do that, we subtract 0.12m from both sides
0.005m + 46 - 0.12m = 0.12m - 0.12m
Step 2: Cancel 0.12m on the right side:
-0.115m + 46 = 0
Step 3: Group constants:
We need to group our constants 46 and 0. To do that, we subtract 46 from both sides
-0.115m + 46 - 46 = 0 - 46
Step 4: Cancel 46 on the left side:
-0.115m = -46
Step 5: Divide each side of the equation by -0.115
-0.115m/-0.115 = -46/-0.115
m = 400
She must talk over 400 minutes for the new plan to be a better deal
Source