1. A newspaper charges $50 per half-page ad and $80 per full-page ad. Gavin has a budget of $750 to purchase 12 advertisements.
(a) Define a variable for each unknown. Write a system of equations to represent the situation
(b) How many half-page advertisements does Gavin purchase? Show your work.
(c) How many full-page advertisements does Gavin purchase? Show your work. Please help

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?