Media Services charges 20$ for a phone and $30 a month for its economy plan.The equation C=30+20 describs the totl cost,c, of operating a Media Services Phone for t months.The Total cost of ten months service is?
If a customer had only 90 dollars how many months of service would this buy?

Question

anonymous · Answer

I assume you meant   C = 30t + 20

anonymous · Answer

yes, sorry.

anonymous · Answer

So for 10 months - substitute 10 in for t

C = 30(10) + 20 
C = 300 + 20
C = 320

anonymous · Answer

The equation should include T, as in: C = 30t + 20
Total cost for 10 months:
$$\Large C=10*30+20$$$$\Large=320$$
To find how long $90 would last, solve for t:
$$\Large 90 = 30t + 20$$

anonymous · Answer

If you only have $90 you would put that into the total Cost
90 = 30t + 20   and solve for the number of months

anonymous · Answer

so the customer would  get about 2.5 months service right?

anonymous · Answer

Around that:
$$\Large \begin{array}{l}
90 = 30t + 20\
30t = 90 - 20\
t = \frac{{70}}{{30}}\
 = \frac{7}{3}
\end{array}$$
Or about 2.333...

anonymous · Answer

yeah okay 2 months, 33 hours and 3 minutes of talk time. lol

anonymous · Answer

Thank you!

anonymous · Answer

No worries :)
Although it would actually be 1/3 of a MONTH... or about 10 days.

anonymous · Answer

I would say 2 months... I don't think they are going to give you a partial month.

anonymous · Answer

Yes blexting is right, given that's it monthly and you cannot exceed the $90 limit, you would have to stop at 2 months.

anonymous · Answer

2 months it is.