To find the result we can use proportion
[tex] \frac{1}{7} --------------- \frac{1}{9} \\ x ---------------1[/tex]
Now we have crossmultiply, so
[tex] \frac{1}{7}*1= \frac{1}{9} *x [/tex] /*9 (multiply both sides by 9)
[tex] \frac{9}{7}=x [/tex] - its the result