Help with question 7

In the proof of the triangle angle sum theorem, you must draw an auxiliary line. which construction must you use to draw this line?

1foot = 12 inches; 1 yard = 3 feet

Two customers went to a post office. first customer paid $12 for 14 and 5 envelopes the second paid 24.80 for 10 postcards and 15 envelopes. what is cost of each envelope?