Question

When solving the equation 4(3x^2 + 2) - 9 = 8x^2 + 7, Emily wrote

Answer 1

1 addition property of equality

Since there the -9 disappeared on the left and the +7 changed by 9 to a +16, 9 must have been added to both sides of the equation, and the addition property of equality states that the equation remains true when the same thing is added to both sides.