y =mx + b m is slope and b is y intercept
(3, 7) ( 7,4) first we solve for the slope, slope formula is m= (y1-y2)/(x2-x1)
m= (4-7)/(7-3)= -3/4 is the slope now we solve for the y, intercept or B.
7 = -3/4 (3) + b
7 = -2.25 + b now we add 2.25 to both sides
9.25 = b now we write the equation using the slope and y intercept
y= -3/4x + 9.25 is your answer