Question

For what value of a are the graphs of 6y=−2x+4 and 2y=ax−5 parallel?

Answer 1

we get that the slope for the first line is

$-\frac{2}{6}=-\frac{1}{3}$

so we ge that

$\frac{a}{2}=-\frac{1}{3}\rightarrow a=-\frac{2}{3}$