simple,
y=mx+c is general form of strainght line
m is the slope.
for 2 lines to be parallel , they must have same slope .
in this case , m=3
any line parallel to given line can be given by y= 3x+c where different values of c give different parallel lines .
now for this line to pass through (9,0) , the point should satisfy the equation of line.
so substitute..... 0=3*9+c
you get c= -27
so
the answer is
y=3x-27
