1/3+3/4+2/5+5/7+7/8+9/20+10/21+11/24+19/35
=(1/3+3/4+7/8+11/24)+(2/5+9/20)+(5/7+10/21+19/35)
=(8/24+18/24+21/24+11/24)+(8/20+9/20)+(75/105+50/105+57/105)
=29/12+17/20+26/15
=145/60+51/60+104/60
=300/60
=5
1/3+3/4+2/5+5/7+7/8+9/20+10/21+11/24+19/35
=(1/3+3/4+7/8+11/24)+(2/5+9/20)+(5/7+10/21+19/35)
=(8/24+18/24+21/24+11/24)+(8/20+9/20)+(75/105+50/105+57/105)
=29/12+17/20+26/15
=145/60+51/60+104/60
=300/60
=5