In which step did emesto make the first error?
emesto tried to determine the solution for the system of
equations using substitution. his work is shown below.
x-y=7
3x - 2y = 8
step 1: x = y + 7
step 2: 3(y + 7) - 2y = 8
step 3: 3y + 7 - 2y = 8
step 4: y + 7 = 8
step 5: y = 1
step 1
step 2
step 3
step 4

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?