m = 3 is the slope of the given line; also its the slope of anything parallel to the given line
(x1,y1) = (1,3) is the given point the parallel line goes through
y - y1 = m(x-x1) .... point slope form
y - 3 = 3(x - 1) .... plug in the given values; solve for y
y - 3 = 3x - 3
y - 3+3 = 3x - 3 + 3
y = 3x + 0
y = 3x
Final Answer: y = 3x
side note: if you plugged in x = 1 it leads to y = 3 which confirms that (x,y) = (1,3) is on this parallel line.