pertanyaan diatas :)

2/x+1/y=1
Disamakan penyebut nya
(2y+x)/xy=1
2y+x=xy

1/x-2/y=8
Disamakan penyebutnya
(y-2x)/xy=8
y-2x=8xy

Eliminasi
2y+x=xy (x2)
y-2x=8xy (x1)
4y+2x=2xy
y-2x=8xy
_________+
5y = 10xy
5 = 10x
x = ½

2y+x=xy (x1)
y-2x=8xy (x2)
2y+x=xy
2y-4x=16xy
_________-
5x = -15xy
5 = -15y
y = -⅓
Maka,
x+y=½-⅓= 1/6
1/(x+y)= 1:1/6 = 6 (E)