2 целых 8/9 * (1/7 + 8/49 ) =
= [ (2*9+8)/9 ] * ( [ (1*7)/(7*7) ] + 8/49) =
= 26/9 * (7/49 + 8/49) =
= 26/9 * [ (7+8)/49 ] =
= 26/9 * 15/49 =
= (26 * 15) / (9*49) =
= (26 *5) / (3*49) =
= 130/147
по действиям:
1) 1/7 + 8/49 = 7/49 + 8/49 = 15/49
2) 2 8/9 * 15/49 = 26/9 * 15/49 = (26 *15)/(9*49) =
= (26 * 5 * 3)/ (3*3*49) = (26*5)/ (49*3) = 130/147