Can you give me proably a little step by step to the answer so I can understand it a bit more?

How do the definitions, properties, and postulates you've learned about line segments, parallel lines, and angles to define the shapes of polygons

Acredit union pays 5% annual interest, compounded daily, on savings deposits. find the value after one year of $500 deposited in this account. $525.64 $25.64 $20.40 $520.40

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?