Tony solves the linear equation 3(x - 3) + 2x + 9 = 2x + 2(x - 1) using the step shown below.



Step 1: 3x - 3 + 2x + 9 = 2x + 2x - 1

Step 2: 5x + 6 = 4x - 1

Step 3: 5x - 4x = -1 - 6

Step 4: x = -7

a
He distributed incorrectly.
b
He incorrectly applied the multiplication and division properties of equality.
c
He incorrectly applied the addition and subtraction properties of equality.
d
He incorrectly combined like terms.