Force exerted by two charges

 P: 35 1. The problem statement, all variables and given/known data Two point charges are placed on the x-axis as follows: one positive charge, q1, is located to the right of the origin at x= x1, and a second positive charge, q2, is located to the left of the origin at x= x2. What is the total force (magnitude and direction) exerted by these two charges on a negative point charge, q3, that is placed at the origin? Use $$\epsilon_{0}$$ for the permittivity of free space. Take positive forces to be along the positive x-axis. Do not use unit vectors. 2. Relevant equations Coulomb's Law: F = $$\frac{1}{4\pi\epsilon_{0}}\frac{\left|q_{1}q_{2}\right|}{r^{2}}$$ 3. The attempt at a solution MasteringPhysics keeps giving me a "Check your signs error". Yet, as far as I can tell, I should be subtracting the force which is going left / the negative direction (ie, q2) from the force going to the right (ie, q1). Any hints? Attached Thumbnails