NEED HELP WITH THIS

Question

Customers of a phone company can choose between two service plans for long distance calls. The first plan has a
$9
monthly fee and charges an additional
$0.15
for each minute of calls. The second plan has a
$15
monthly fee and charges an additional
$0.11
for each minute of calls. For how many minutes of calls will the costs of the two plans be equal?

Answer 1

Hi Naila,

 

This is a fairly basic algebra word problem.  We need to create an equation for each plan which defines the amount of the bill under each plan.  Then we simply set them equal and solve for the number of minutes when they are equal.

 

We will define MB1 as the monthly Bill for plan 1, and MB2 similarly for plan 2 and M is the number of minutes used

 

Plan 1 : MB1 = $9 + $0.15 * M

 

Plan 2 : MB2 = $15 +$0.11 * M

 

Set them equal :  $9 +$0.15 * M = $15 +$0.11 * M

 

$0.15 * M - $0.11 * M = $15 - $9

 

$0.04 * M = $6

 

M = $6 / $0.04

 

M = 150 minutes

 

I hope this helps

 

Sincerely,

Ralph K.