If $\frac1x+\frac1{2x}+\frac1{4x}=1$, then x=?

A fraction becomes 1/2 if 2 is added to the numerator and 5 is added to the denominator. It also becomes 1/3 if 2 is subtracted from both the numerator and denominator. Then the fraction is

6/7 + 8/7 =?

What should come in place of the question mark (?) in the following questions?

$\frac{6}{2}\times\frac{10}{2}\div{\frac{6}{2}}\times{\frac{6}{2}}\times{6^2}=?$

(1-1/2)(1-1/3)(1-1/4)=?