Can someone help with these. I need to find the sum of the vectors. If you can’t read them, there is -7.0, 5.0, and 8.0

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

What will a positive and a negative charge do if they are separated from each other?

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects