(8/15+3/4)-(7/12+1/5)
= 8/15 + 3/4 - 7/12 - 1/5 = 8/15 - 3/15 + 9/12 - 7/12 = 5/15 + 2/12 = 1/3 + 1/6 = 2/6 + 1/6 = 3/6 = 1/2