a)11/4+5/6+2/5=165/60+50/60+24/60=239/60
b)7/30+5/6+4/15+1/2=7/30+25/30+8/30+15/30=55/30
c)1/4+1/2+3/8+5/12=12/48+24/48+18/48+20/48=74/48
d)3/11+4/3+3/1=9/33+44/33+99/33=152/33
e)3/4+1/6+17/9+7/8+19/36=54/72+12/72+136/72+63/72+38/72=303/72
f)2/3+3/4+4/5+5/6=40/60+45/60+48/60+50/60=183/60