Ответы и объяснения

2014-04-09T19:58:00+04:00
3/7 * (1/4+4/9) = 25/84
1) 1/4 + 4/9 = 9/36 + 16/36 = 25/36
2) 3/7 * 25/36 = 1/7 * 25/12 = 25/84