Jessica wrote a long letter to her aunt and needed to put stamps on it to mail it. She used eight pieces of paper that weigh 1/5 of an ounce each, and her envelope weighs 2/5 of an ounce. She needed one stamp per ounce. How many stamps did Jessica need to mail her letter? Think carefully first, then make a decision:
Jessica's papers weigh 8 * 1 / 5 = 8 / 5 ounces. The papers in the envelope weigh 8 / 5 + 2 / 5 = 10 / 5 = 2 ounces. Thus, Jessica needs 2 * 1 = 2 stamps to mail her letter. So, the answer is 2.