A
acteyro123


1/2 + 1/3 + 1/4 + ..... + 1/18 + 1/19 + 1/20
a=-------------------------------------------------------------
19/1 + 18/2 + 17/3 + ...... + 3/17 + 2/18 + 1/19
a=-------------------------------------------------------------
19/1 + 18/2 + 17/3 + ...... + 3/17 + 2/18 + 1/19