Hi Candidate,

The force exerted on the back and the back are exerted due to Friction forces. The friction force is because of the shear force between the two surfaces and it acts opposite to the motion of body.

The friction force on the back is =u*m*g which is equal to 0.8*56*10= 448 Newton. The friction on the wall = u*m*g which is equal to 0.6*56*10= 336 Newton. These two friction force is equal to (336+448)N= 784 Newton.

But, the weight of the climber is equal to mg= 56*10=560 Newton. So, the actual friction force acting on the climber is just equal to the weight of the climber. So, the friction force acting on the body is equal to 560 Newton just to balance the weight.

Hope, that this answer helps you!!