Question

1比（X+5） +1比（X+8） =1比(X+6) +1比(X+7)

Answer 1

1/(x+5)+1/(x+8)=1/(x+6)+1/(x+7)

(2x+13)/(x+5)(x+8)=(2x+13)/(x+6)(x+7)

(2x+13)[(x+6)(x+7)-(x+5)(x+8)]=0

(2x+13)*2=0

x=-13/2