Question 3
A first straight cut divides a square sheet into two polygons. Each subsequent move divides any one resulting polygon into two by a straight cut. No folding and no cutting two papers together are allowed. Find the minimum cuts needed to obtain, together with any other polygons: (a) two polygons with exactly 20 sides each; (b) three polygons with exactly 30 sides each; (c) four polygons with exactly 60 sides each.