Yurem is pulling a wagon across the playground with a force of 10 n. he asks elianna to . she agrees and pushes the back of the wagon in the same direction with a force of 12 n. what is the net force acting on the wagon?

So we want to know what is the net force on the wagon if Yurem is pulling the wagon with a force of 10 N and Elianna is pushing the same wagon with a force of 12 N. So since both Elianna and Yurem are applying the force in the same direction we simply add both forces together to get the net force which is 10 N + 12 N = 22 N. So the net force acting on the wagon is 22 N. 

490 n  f=125n a=2.5m/s2

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current