Plz plz plz help. Plz​

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

Question 4 of 10 2 points what is the second part of the process of investigating a question using data? a. rephrasing the question o b. describing the data c. collecting the data o d. making an inference submit

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?