5/6 + 2/4 = 11/15 - 3/10

5/6 + 2/4 = (5*2)/(6*2) + (2*3)/(4*3) = 10/12 + 6/12 = 16/12 = 4/3

11/15 - 3/10 = (11*2)/(15*2) - (3*3)/(10*3) = 22/30 - 9/30 = 13/30

Ответ: 4/3 = 13/30