Answer:
a = -2
Explanation:
Ok, so for parallel lines you need to make slopes for both the lines equal. So for line y = x + 4 the slope is 1. (slope is the coefficent infront of the x value while in y=mx+b form. To make the other line have a slope of 1 a needs to be a number as so that 2a+5 = 1
2a+5 = 1
2a = 1 - 5
a = -4/2
a = -2