Media Services charges $20 for a phone and $30/month for its economy plan. The equation c=30t+20 describes the total cost, c, of operating a Media Services phone for phone for t months.
The total cost for 2 months of service is $
If a customer has only $90 available, how many months of service can she receive?

Question

Media Services charges $20 for a phone and $30/month for its economy plan.  The equation c=30t+20 describes the total cost, c, of operating a Media Services phone for phone for t months.
The total cost for 2 months of service is $
If a customer has only $90 available, how many months of service can she receive?

anonymous · Answer

the total cost for two months is
if c=30(t)+20  ,t is the variable for months
therefore sub t=2 in eqn
c=30(2)+20 =80

to find months of service, make t the subject
t=c-20/30
t= (90 - 20 )/30
t = 2   1/3