Need help with Questions 3 and 4

Question 3 1 pts For the previous question, find the electric field (in newtons/coulomb) at the position of the test charge. Again, supply a positive value if the electric field points to the right and a negative value if it points to the left. Do not include units with your answer.Question 4 0.5 pts A xed system of charges exerts a force of magnitude 21 N on a 7.0 C charge. The 10 C charge is replaced with a 4.0 C charge. What is the exact magnitude of the force (in N} exerted by the system of charges on the 4.0 C charge? Do not include units with your