P can do$(1/4 )\mathrm{th}$ of work in 10 days, Q can do $40 \%$ of work in $40$ days and R can do $(1/3)\mathrm{rd}$ of work in $13$ days. Who will complete the work first?

According to question

P can do $=\frac{1}{4}\mathrm{th}$ part of work in$10$days; 

So entire work is done in $10 \mathrm{x} 4 = 40$ days.

Q can do $40 \%$ of work in $40$ days; 

So$100 \%$ work is done in $100$ days

R can do $=\frac{ 1}{3}\mathrm{rd}$ part of work in $13$ days;

 So entire work is done in $13 \mathrm{x} 3 = 39$ days.

$\therefore$R will complete the work first.