Find the unknown entries o, b, c, d, e

On comparing last two tables, we get

$a=12$

$\therefore \quad 12+b=25$

$\Rightarrow$ $b=25-12=13$

$22+b=c$

$\Rightarrow$ $c=22+13=35$

$22+b+d=43$

$\Rightarrow \quad 22+13+d=43$

$\Rightarrow \quad d=43-35=8$

and $\quad 22+b+d+e=48$

$\Rightarrow \quad 22+13+8+e=48$

$\Rightarrow \quad e=48-43=5$

and $\quad 24+b+d+e=f$

$\Rightarrow \quad 24+13+8+5=f$

$\therefore \quad f=50$