Euler formula (x: black skin, y: white skin). (5x+6y)/3+(x+y)-(5x-6y)/2 = 2: x =12 (1) Black leather * * How many sides: 65438. These 60 edges are stitched together with white leather. For white leather, three of the six sides of each white leather are sewn together with the side of the black leather, and the other three sides are sewn together with the sides of other white leather, so half of all the sides of the white leather are sewn together with the black leather, so the white leather should have 60× 2 = 65438+.