Найдите значение выражения: а) 3/7 * (1/4+4/9);
б)4/5 - 1/4 : 5/6

а) 3/7 * (1/4 + 4/9) = 25/841) 1/4 + 4/9 = 9/36 + 16/36 = 25/362) 3/7 * 25/36 = (1*25)/(7*12) = 25/84б) 4/5 - 1/4 : 5/6 = 5/10 = 0,51) 1/4 : 5/6 = 1/4 * 6/5 = (1*3)/(2*5) = 3/102) 4/5 - 3/10 = 8/10 - 3/10 = 5/10