Выполните действия 7/15+1/5=?-1/3=?+1/4 7/15-1/15=?+1/20=?+1/3 7/15+1/3=?+1/5=?-5/12 посчитайте

10/15 - 3/15 = 7/15 ( 7/15 = 28/60) 28/60 + 20/60 = 48/60

6/15 ( 24/60 ) 24/60 + 3/60 = 27/60 + 20/60 = 47/60

12/15 + 3/15 = 15/15 ( 15/15 = 1 ) 1 - 5/12 = 12/12 - 5/12 = 7/12