34+51 17*2+17*3 17*(2+3)
а) ---------------- = -------------------- = ------------------- = 5/3 = 1 2/3
68-17 17*4 - 17 17*(4-1)
136*21 136*3*17 136*3*17 408
б) ---------------- = ----------------- = ---------------- = ----------- = 34
85+119 17*5+17*7 17*(5+7) 12