5/7*(21/20-7/30)+16/21:8/7
калькулятор не?
5/7* (21/20 -7/30) + 16/21 / 8/7= 5/7(63/60 -14/60) +2/3 = 5/7 * 49/60 + 2/3 = 7/12 +2/3= 7/12 +8/12 = 15/12 = 1 3/12 = 1,25