The line on the left passes through the y axis at x = 3 so it is y = 2x + 3.
b. The line 2x + 1 will be parallel to the other 2 lines because the slope (2 - from the '2x') is the same. It will pass through the y axis at y = 1.
c. The lines -2x + 1 would pass through the y axis at y = 1 but the the slope which is negative 2 will rise to the left unlike the other 3 lines which rise to the right. It will intersect the line y = 2x + 1 at the point (0,1) - where y = 1.