Was there something confusing about the help posted here?
http://www.jiskha.com/display.cgi?id=1384483325
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.
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
5 answers
so is it 886.2
yes.
ok and then for the one that said find the household cost of telephone service in 2000
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.
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.