Nilai x.y/x+y pada sistem persamaan 2x-3y=0 dan 8x+6y=5 adalah

2x-3y=0 ( X 2) 4x – 6y = 0
8x+6y=5 ( X1 ) 8x + 6y = 5
====================== +
12x = 5
x = 5/12

8x + 6y = 5
8(5/12) + 6y = 5
40/12 + 6y = 5
10/3 + 6y = 15/3
6y = (15-10)/3 = 5/3
y = 5/18

xy = 5/12 X 5/18 = 25/216
x + y = 5/12 + 5/18 = (15+10)/36 = 25/36
xy/(x+y) = xy : ( x + y)
= 25/216 : 25/36
= 25/216 x 36/25
= 36/216
= 1/6