How can I solve this? I couldnt figure it out so I just requested the answer. But how can I solve this kind of question for the future, in case a similar problem shows up on the test? Specifically Part B of this problem?

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

Aballet student who learns with the of his instructor is demonstrating learning.

How is zig zagging a form of acceleration?