For a company picnic, Todd fills 30 paper cups with ketchup and Yuki fills 27 paper cups with ketchup. Each paper cup holds 1 ounce. Later, Todd and Yuki learn that two other company employees completed exactly the same task. How many ounces of ketchup did the four employees prepare?

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?