Step-by-step explanation:
I'd 5261333821 . p. 12345 on z.o.o.m
let , $a\ge b$
$\therefore a=G\cdot m$ and $b=G\cdot n$
$a-b=Gm-Gn=G(m-n)$
Now, $\gcd(a-b,b)$ clearly is, $G$
Line through (-4,0) and (0,-2)
Slope is change in y over change in x
m = (-2 - 0)/(0 - -4) = -2/4 = -1/2
Answer: -2/4 = -1/2, second choice