(5/6 - 3/10 ) : (3/10 + 2/15) = 1 3/13
выражением:
= (25/30 - 9/30) : ( 9/30 + 4/30) =
= 16/30 : 13/30 =
= 16/30 * 30/13 =
= 16/13 = 1 3/13
по действиям:
1) 5/6 - 3/10 = (5*5 - 3*3) /30 = (25-9)/30 = 16/30 = 8/15
2) 3/10 + 2/15 = (3*3 + 2*2)/30 = (9+4)/30 = 13/30
3) 8/15 : 13/30 = 8/15 * 30/13 = (8*2)/(1*13) = 16/13 = 1 3/13