y = mx + b
slope(m) = 3/2
(5,9)...x = 5 and y = 9
now we sub and find b, the y int
9 = 3/2(5) + b
9 = 15/2 + b
9 - 15/2 = b
18/2 - 15/2 = b
3/2 = b
so ur equation is : y = 3/2x + 3/2.........(3,a)....so x = 3
y = 3/2(3) + 3/2
y = 9/2 + 3/2
y = 12/2
y = 6
so ur missing value is 6...a (or y) = 6
