Ответы и объяснения

2013-12-13T11:42:02+00:00
3/4 + 2/3 = 9/12 +8/12 = 17/12 =  1ц 5/12
 3/5-1/3 =  9/15 -5/15 = 4/15
 3/4-3/2 = 3/4 -6/4 = - 3/4
 3/4 + 3/14 =  21/28 +6/28 = 27/28