Сколько будет (1 11/18+13/24-1 13/36)*1 3/5

(1 11/18 + 13/24 - 1 13/36) * 1 3/5 = 1 4/15

1) 1 11/18 + 13/24 = 1 44/72 + 39/72 = 1 83/72
2) 1 83/72 - 1 13/36 = 1 83/72 - 1 26/72 = 57/72 = 19/24
3) 19/24 * 1 3/5 = 19/24 * 8/5 = (19*1)/(3*5) = 19/15 = 1 4/15 

Общий знаменатель 72
72 : 18 = 4 - доп.множ. к 11/18 = (11*4)/(18*4) = 44/72
72 : 24 = 3 - доп.множ. к 13/24 = (13*3)/(24*3) = 39/72
72 : 36 = 2 - доп.множ. к 13/36 = (13*2)/(36*2) = 26/72
57/72 = 19/24 - сократили на 3