Question 283875
You are going to write an equation for a straight line 
with the year as x and the cost as y
x=year-1950
1950+x, y=.25
2010+x y=3.25 
x=2010-1950=60 years since 1950
325-25=300
300/60=.05 cents per year
when x=0 the year is 1950 so the hamburger cost .25
y=.25+.05x your formula not really needed but it works

y= cost x=years since 1950
plug in 60 for x and find y=3.25
plug in 0 for x and get .25 for y