Answer:
the equation of a straight line is y = m x + b where m is the slope and
b is the y intercept at x = 0
so y1 = x1 + b and y2 = m x2 + b where (x1, y1) and (x2, 2 are points on the line.
y2 - y1 = m (x2 - x1) or m = (y2 - y1) / (x2 - x1)
For the given points
m = ( 10 - 4) / (2 - 7) = - 6 / 5 for the slope