David's utility function is u(x, y) = 4x + 3y. The price of x is $6, the price of y is $6 and his income is $120. The price of x drops to $4, the price of y and his income remain the same. Calculate the total, substitution and income effects for his consumption of x due to the price change of x. On a clearly labeled graph, illustrate those three effects of the price change on his consumption of x