The working is correct, BUT, they did not substitute their x values in which they have found into one of the equations to determine the y values. By using x = 3 and x = -2, sub them into equation 2 (mainly since it is simpler),
x = 3, x = -2
y = 4x + 1 y = 4x + 1
= 4(3) + 1 = 4(-2) + 1
= 13 = -7
Therefore, the correct points of intersection are (3 , 13) and (-2 , -7)
Hope this helped!