The equation of the line below can be expressed in the form
\frac{x}{a} + \frac{y}{b} = 1.
Find a.
The lines passes through (5,8) and (-4,17).
First, find the slope as (y1-y2) /( x1-x2) = (8-17)/(5 - -4) = (-9)/(9) = - 1
Then the line in mx+b form is
y = (-1) x + b sub in the values of either point to find b = 13
so the equation becomes
y = -x + 13 re-arrange
x +y = 13 divide thru by 13
1/13x + 1/13 y =1