Solve for part a and b

The drawing shows a positive point charge +q1, a second point charge q2 that may be positive or negative, and a spot labeled P, all on the same straight line. The distance d between the two charges is the same as the distance between q1 and the spot P. With q2 present, the magnitude of the net electric field at P is twice what it is when q1 is present alone. Given that q1 = +0.70 HC, determine the magnitude |q2| when q2 is (a) positive 1921 = i 2.80E-6 UC and (b) negative. 1921 = i 2.80E-6 HC P 42 + 91 d d