How to find equation from given data?

[tantrik]

Dear friends,

I am unable to solve the following problem. Will appreciate your help here. Thanks in advance.

The Purple Mobile Phone Company offers the following two pricing plans to customers. Plan A costs \$15/month, with calls at 25c/minute, while Plan B costs \$100/month with calls at 14c/minute. Find an equation that gives C, the cost in dollars, in terms of t, the call time in minutes per month for each plan.

 

[HallsofIvy]

Dear friends,

I am unable to solve the following problem. Will appreciate your help here. Thanks in advance.

The Purple Mobile Phone Company offers the following two pricing plans to customers. Plan A costs \$15/month, with calls at 25c/minute, while Plan B costs \$100/month with calls at 14c/minute. Find an equation that gives C, the cost in dollars, in terms of t, the call time in minutes per month for each plan.

You are given t in minutes and want to get C in dollars. There is a "cents/minute" so multiplying by t in minutes will result in cents. Dividing that by 100 cents/dollar will put it into dollars. The monthly cost is already in dollars so you can just add that:
C= 15+ (25/100)t

C= 100+ (14/100)t.

 

[tantrik]

You are given t in minutes and want to get C in dollars. There is a "cents/minute" so multiplying by t in minutes will result in cents. Dividing that by 100 cents/dollar will put it into dollars. The monthly cost is already in dollars so you can just add that:
C= 15+ (25/100)t

C= 100+ (14/100)t.

Thanks for your explanation and working for the problem.