+45 A merchant bought several pieces of silk for $70. He sold all but two of them at a profit of $4 per piece. His total profit was $18. How many pieces did he originally purchase?
+23246 Let n be the number of pieces. He sold n - 2 pieces
Let p be the original price. His selling price = p + 4
Then n · p = 70.00
And (n - 2) · (p + 4) = 88.00 ---> np + 4n - 2p - 8 = 88.00
---> np + 4n - 2p = 96.00
---> 70.00 + 4n - 2p = 96.00
4n - 2p = 26.00
2n - p = 13.00
Trying some possibilities (7 & 1), (8 & 3), (9 & 5), and (10 & 7), finally gets us to the answer: n = 10 and p = 7.00.
