qsub1:-2.8uC

qsub2: 6.6uC
qsub2 sits 7.9 cm away from qsub2, and in a previous question moved up the y axis 2.7cm. The question that I am having difficulty with has added qsub3 in the middle of of qsub1 and qsub2, changing the magnitude of Fsub2net= 7.954. What is the sign and magnitude of qsub3?

Megurine, no... I think I am having trouble solving for q3 using both Coulomb's Law and the superposition principle. So far I have

31.78326213+Fsub3=7.954