We want to calculate the line that passes through the points (-7,0) and (-3,-9). Recall that the equation of a line is
where m is the slope and b is the y intercept. We can calculate first the slope and then find the value of b. To do so, recall that given points (a,b) and (c,d) the slope of the line that passes through them is given by the formula
so by taking a=-7, b=0, c=-3 and d=-9 we get
so our equation becomes
so know we want this line to pass through the point (-7,0), so whenever x= -7 then y=0 so we have the equation
or equivalently
so if we subtract 63/4 on both sides, we get
so our equation would be