(a) What is the electric field strength due to a point charge of 2.4 microcoulombs at a position 8.6 cm away from the charge?
(b) What is the magnitude of the electric force on a charge of −3.4 microcoulombs that is 8.6 cm away from the point charge in part a?

For (b) what do I use for the values of q1 and q2? Would I plug in both the 2.4 microcoulombs and the -3.4 microcoulombs charges?