What is the net force on a cart that is pulled to the right with 100 pounds of force and to the left with 30 pounds of force?

The answer to your question is: F = 70 pounds

Explanation:

To calculate the net force, only substract the left value to the right value.

                                F = F right  -  F left

                                F = 100 p - 30 p

                                F = 70 pounds

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.