The equation of the line passing through (1,11) and (-4,5) can be expressed in the form x/a + y/b = 1. Find a.
+600 I like $y=mx+b$ form better, so I'll use that. We have:
$11=m+b, 5=-4m+b$. Subtracting, $5m=6\implies m=\frac{6}{5}$
And $b=11-m=\frac{49}{5}$.
So $y=\frac{6}{5}x+\frac{49}{5}\implies -\frac{6}{5}x+y=\frac{49}{5}\implies -6x+5y=49\implies -\frac{6}{49}x+\frac{5}{49}y=1$. So $a=\boxed{-\frac{49}{6}}$.
