How can you find the net force if two forces act in opposite directions?

If two forces act in exactly opposite directions, then the magnitude

of the net force is their difference, and the direction of the net force

is the direction of the greater one.

Examples:

10 newtons up, 4 newtons down, net force = 6 newtons up

24 pounds left, 20 pounds right, net force = 4 pounds left

999,999 ounces forward, 1 million ounces backward, net force = 1 ounce backward