Marcel made an error when he used the distributive property to solve the problem shown. Which sentence describes the error? In Step 2, 90 should be multiplied by the quantity 10 – 12, not by 10. 10 was substituted for x at the wrong step. In Step 1, the expression should be x(90 – 12) not 90(x– 12). There should be no parentheses in Step 1. It should be 90 • x – 12.

Statements reasons 1. ab ? cd; ad ? bc 1. given 2. ac ? ac 2. reflexive property 3. ? adc ? ? cba 3. ? 4. ? dac ? ? bca; ? acd ? ? cab 4. cpctc 5. ? dac and ? bca are alt. int. ? s; ? acd and ? cab are alt. int. ? s 5. definition of alternate interior angles 6. ab ? cd; ad ? bc 6. converse of the alternate interior angles theorem 7. abcd is a parallelogram 7. definition of parallelogram what is the missing reason in step 3?