Glencoe Algebra 2, Chapter 2, 2.4, Section 2.4, Problem 8

Given the points are
(x_1,y_1) =(6,1)
and
(x_2,y_2) =(8,4)
the slope of the line passing through the points is given as
m = (y_2 - y_1)/(x_2 - x_1)
= (4-1)/(8-6)
= 3/2
so the slope is 3/2
as the
slope m= 3/2
and the line passes through the point (x,y)= (6, 1)
the slope-intercept form of a line is
y= mx+b
from the above we know m = 3/2 , so the line equation is
y= (3/2)x+b --------------(1)
we need to find the value of b , as the line passes through the point
(x,y)= (6, 1 ) , then on substituting we get
1 =(3/2)*(6)+b
=> b = 1- (9) = -8
so the equation of the line is
y= (3/2)x-8