Please hellp thank you

Heres on ex.

When the driver of a bus applies brake suddenly, the lower part of the body comes to rest as the bus comes to rest but, the upper part of the body continues to move forward due to inertia of motion.

Explanation:

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)