= (1- $\frac{1}{12}$) + (1- $\frac{1}{20}$) + (1- $\frac{1}{30}$) + (1- $\frac{1}{42}$) + (1 - $\frac{1}{56}$)
= 5 - ($\frac{1}{12}$ + $\frac{1}{20}$ + $\frac{1}{30}$ + $\frac{1}{42}$ + $\frac{1}{56}$)
= 5 -( $\frac{1}{3×4}$ + $\frac{1}{4×5}$ + $\frac{1}{5×6}$ + $\frac{1}{6×7}$ + $\frac{1}{7×8}$)
= 5 - ( $\frac{1}{3}$ - $\frac{1}{4}$+$\frac{1}{5}$ + $\frac{1}{5}$-$\frac{1}{6}$ + $\frac{1}{6}$ - $\frac{1}{7}$ + $\frac{1}{7}$ - $\frac{1}{8}$)
= 5- ($\frac{1}{3}$ - $\frac{1}{8}$)
= 5 - $\frac{5}{24}$
= $\frac{115}{24}$
