What is the point slope form of the line with slope −3/7 that passes through the point (5, 8)?

They are asking for point slope form, so we need to grab the equation:
y - y1 = m(x - x1)

Then just plug in what we already know:
m = -3/7 , y1 = 5 , x1 = 8

y - 5= -3/7(x - 8)

Then solve for Y

Final y = -3/7x + 71/7

A’b’c’ are the coordinates to the new location of the transformed triangle abc. find the distance between the coordinates points to use for your calculations.