the annual household cost of telephone service in the US increased at a relatively constant rate of $27.80 per year from 1981 to 2001. in 2001 the annual household cost of telephone service was $914.

Question

a: what was the annual household cost of telephone service in 1981?

b: write an equation that gives the annual household cost of telephone service as a function of the number of years since 1981.

c: find the household cost of telephone service 2000

Answer 1

Was there something confusing about the help posted here?

http://www.jiskha.com/display.cgi?id=1384483325

Answer 2

so is it 886.2

Answer 3

yes.

Answer 4

ok and then for the one that said find the household cost of telephone service in 2000

Answer 5

Well, since 886.2 = 914 - 27.80, that is the cost in 2000.

Now, if you want to find the cost in 1981, then you have to solve

x + 27.80*20 = 914

That is, we know the cost after 20 years (914), but we want to find out where it started.