hasil dari 1/x + 1/y : 1/x - 1/y adalah

(1/x + 1/y) : (1/x - 1/y)
= (y/xy + x/xy) : (y/xy - x/xy)
= ((y+x)/xy) : ((y-x)/xy)
= (y+x)/xy * xy/(y-x)
= (y+x)/(y-x)
= (x+y)/(-x+y)
= (x+y)/(x-y)*(-1)
= - (x+y)/(x-y)
jawabannya B.
note: -1 berasal dari -x+y...