The way to solve if a point is on the line is by plugging in the points and seeing if the equation works. So first find the equation using:
y = mx + b where m is slope and b is y intercept
5 = - 3/4 * - 2 + b
5 = 6/4 + b
b = 7/2
so the equation for the line is:
y = - 3/4x + 7/2
If a point to be tested was (0,0) then we plug this point in equation:
0 = - 3/4 * 0 + 7/2
0 = 7/2
since this is not true this point does not lie in the line