I was doing this textbook problem and I don't get this. Some help will be appreciated

(1) A small spherical insulator of mass 8.00 x 10 2 kg and charge +0.600 uC is hung by a thread of negligible mass. A charge of -0.900 JC is held 0.150 m away from the sphere and directly to the right of it, so the thread makes an angle O with the vertical (see the drawing). Find (a) the angle o and (b) the tension in the thread. 0. 150 m +0.600 /C -0.900 MC