A merchant gains or loses, in a bargain, a certain sum. In a second bargain, he gains 450 dollars, and, in a third, loses 30. In the end he finds he has gained 100 dollars, by the three together. How much did he gain or lose bv the first ?
Select:
A) 320
B) -340
C) -320
D) 348
E) None
In this sum, as the profit and loss are opposite in their nature, they must be distinguished by contrary signs. If the profit is marked +, the loss must be -.   Let x = the sum required.   Then according to the statement x + 450 - 30 = 100   And x = -320.   Answer -320
<result>C</result>
A merchant gains or loses, in a bargain, a certain sum. In a second bargain, he gains 450 dollars, and, in a third, loses 30. In the end he finds he has gained 100 dollars, by the three together. How much did he gain or lose bv the first ?