In America it is common that odds are displayed with a plus- or a minus-sign. An odd with a plus sign means how much you could win with a stake of 100 dollar. Does the odd show a minus sign it means how much you have to place to earn a profit of 100 dollar.
Example: Odd +250
At a stake of 100 Dollar you can win 250 Dollar.
Example: Odd -160
Means that with a stake of 160 Dollar you will achieve a 100 Dollar net profit.