Assuming the question is to find the equation of the line passing through those two points:
Step 1: Find the slope of the line
The slope #m# of a line passing through the points #(x_1, y_1)# and #(x_2, y_2)# is given by
#m = (y_2-y_1)/(x_2-x_1)#
Substituting the given points in, we get
#m = (7 - 0)/(9 - (-3)) = 7/12#
Step 2: Write the equation of the line in point-slope form
The point-slope form of a line with slope #m# and passing through the point #(x_1, y_1)# is
#y - y_1 = m(x-x_1)#
Substituting one of the given points and our slope, we get
#y - 0 = 7/12(x - (-3))#
#=> y = 7/12(x+3)#
Step 3: Convert the equation into standard form
The standard form of a line is #Ax + By = C# where, if possible, #A,B,# and #C# are integers without a common factor. We perform algebraic manipulations on the above equation until it matches this form.
#y = 7/12(x+3)#
#=> y = 7/12x + 7/4#
#=> -7/12x + y = 7/4#
#:.-7x + 12y = 21#