Это было долго :D
а) 32 и 48, 32 и 24, 32 и 56, 48 и 24, 48 и 72, 48 и 56, 24 и 72, 24 и 56, 72 и 56
б) 27 и 48, 27 и 24, 27 и 72, 27 и 18, 27 и 15, 27 и 30, 48 и 24, 48 и 72, 48 и 18, 48 и 15, 48 и 30, 24 и 72, 24 и 18, 24 и 15, 24 и 30, 72 и 18, 72 и 15, 72 и 30, 18 и 15, 18 и 30, 15 и 30
в) 15 и 30, 15 и 55, 15 и 35, 30 и 55, 30 и 35, 55 и 35