Aboy pulls a wagon with a force of 6 n east as another boy pushes it with a force of 4 n east. what is the net force?

Both boys are applying forces to the wagon in the same direction,
so the result of both of them is a simple sum of the individual
magnitudes, and still in the same direction.

That's         (6N east + 4N east)  =  10 N east.

That's the net force due to the two boys. 
IF there are no OTHER forces on the wagon,
then it's also the net force on the wagon.                 10 N east