Question 1204992
Question asks for a linear function.  Description describes one point and a slope.    Those go this way.  A point (x,y) is  (250, 100), and slope is {{{-8/20=-4/10=-2/5}}}.


Now, you know what to do with this, if you may start with the point-slope form.


{{{y-100=-(2/5)(x-250)}}}.
Solve and simplify this for y, in the form of y=mx+b.