Answer:
Step-by-step explanation:
The first thing to do is convert to a common denominator.
So 1/2 =4/8. That means the vendor sold 4/8+3/8=7/8 of its hot dogs. 280 = 7/8. Now if you divide 280 by 7, you get 1/8 (answer = 40). The vendor sold 7/8 and 1/8 was left, which = 40. 8/8 would be 280 + 40 = 320.