There is a sport of climbing between two vertical walls. As shown in the picture below, the wall climber remains static between two walls without falling. The reason is that a friction force counter-acts the gravitational force that pulls down the climber. The climber exerts a force of 800 N to the wall, the kinetic friction coefficient between the climber and the wall is 0.7. The climber weighs 700 N. The maximum static friction is 750N.

Calculate the magnitude of the friction force