A child slides across a floor in a pair of rubber-soled shoes. The friction force acting on each foot is 25 N, the cross-sectional area of each foot is 20 cm2, and the height of the soles is 5.0 mm. Find the horizontal distance traveled by the sheared face of the sole. The shear modulus of the rubber is 3.0 x 10^6 Pa. I used F/A=S*(deltaX/n) plugging in 20/14=3x10^6(deltaX/.5) but didn't get the right answer.