Let's assume
number of months =x
A high definition radio station charges $200 per year
so, we get point as (0,200)
Assume
f(x) is the total amount of charges in a year
we can see that this is linear relationship
so, we can use formula
[tex]f(x)=mx+b[/tex]
in addition to $50 per month for the first 3 months to receive its broadcast
so, m=50
we can plug it
[tex]f(x)=50x+b[/tex]
we can use point as (0,200)
[tex]200=50*0+b[/tex]
[tex]b=200[/tex]
now, we can plug it back
and we get
[tex]f(x)=50x+200[/tex]...............Answer