If 3x−4y+5=0 and ax+2y+4=0 are parallel to each other then a=

Two lines a1x+b1y+c1=0  and a2x+b2y+c2=0 are parallel if and only if  a1a2=b1b2It implies that   3a=−42Cross multiply and then simplify  −4a=6a=-32 Therefore, the value of a is   a=-1.5