A student saves money to buy a laptop. The student already has $ 307.50 saved and puts aside $ 100 each month to help pay for the laptop. After 5 months, the total amount saved is 75 % of the total cost of the laptop. How much more does the student need to save to buy the laptop rounded to the nearest cent?

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?