If to make a pattern of matchsticks, 50 matchsticks are required, how will you write the total number of matchsticks required for b number of such patterns?

Given that 50 matchsticks are required for a pattern.

So, for b number of such patterns, 

The total number of matchsticks =  Number of matchsticks for one pattern $\times$b

 =  $\mathrm{b} \times 50 = 50\mathrm{b}$.

Hence, The total number of matchsticks required for b number of patterns is 50b.