The equation of a straigth line is
y = mx + c
m = slope
from the question slope = 9
our points are (5,4)
y - y1 = m(x - x1)
x1 = 5 and y1 = 4
y - 4 = 9(x - 5)
y - 4 = 9 * x - 9 *5
y - 4 = 9x - 45
y = 9x -45 + 4
y = 9x - 41
The answer is y = 9x - 41
