In a construction company, a supervisor claims that 7 men can complete a task in 42 days. In how many days will 14 men finish the same task?

Consider the number of men is M and the number of days is D.
Given:  M₁ = 7 ,  D₁ = 42, and  M₂ = 14.

This is an inversely proportional relation, as if the number of workers increases, the number of days decreases.

M ∝ $\frac{1}{\mathrm{D}}$

Considering the first situation, M₁ = $\frac{\mathrm{k}}{{\mathrm{D}}_1}$

7 = $\frac{\mathrm{k}}{42}$

k = 7 × 42 = 294

Considering the second situation,  $M_2$ = $\frac{\mathrm{k}}{{\mathrm{D}}_2}$

14 = $\frac{294}{{\mathrm{D}}_2}$

$D_2$ = $\frac{294}{14}$ = 21

Hence, It will take 21 days for 14 men to do the same task.