If force c is 30n and force d us 20 N what is the size of the horizontal force

Polly is pushing a box across the floor with a force of 30 n. the force of gravity is –8 n, and the normal force is 8 n. which value could describe the force of friction if polly could not move the box?

Infrared radiation has wavelengths that are shorter than visible light is part of the visible light spectrum has wavelengths that are longer than visible light has the same wavelengths as ultraviolet radiation

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.