7-3/4= 3+7/4+7*7+15/12+8= (8/3+2/3)+(7/18+8/18)= 2/3+7/3*4/5-1/5=

1) = 12/4+7/4+49+5/4+8 = 57 + 24/4 = 63 
2) 10/3+18/18 = 20/6 + 5/6 = 25/6 
3) 2/3+28/15-1/5=10/15+28/15-3/15=35/15 = 7/3