Answer:
a=12
Explanation:
we need the slope of this line. Find it with the slope formula
m= y2-y1 / x2-x1 with the points given p1=(-8,7) and p2=(-11,-11)
m=-11-7 / -11-(-8) (x1,y1) (x2,y2)
m= -18 /-11+8
m= -18 / - 3
m= 6
next plug in one of the point into the point-slope formula [y-y1=m(x-x1)]
y-7=6(x-(-8)) ( simplify this towards the slope intercept form [y=mx+b]
y-6=6(x+8)
y-6=6x+48
y=6x+54
now we can plug in our point of (-7,a) to find what a is
a=6(-7)+54
a=-42+54
a=12
:)