Describe the relationship between minutes and monthly cost

Question

Minutes = X

monthly cost= Y

Linear Equation is Y=5x+30 (y=mx+b)

Answer 1

I'll have to be a little presumptive here as to what you are asking, but from what you have written I would say, every minute the cost increases by $5. This is the variable cost. The fixed cost, independent of how many minutes, is $30.

This might describe a phone plan that cost you $30 a month, plus $5 a minute. (YIKES!)