For a unidirectional first order decomposition:
$X\text{(}g\text{)}\underset{ }{\overset{ }{\to }}Y\left(g\right)+2Z\left(g\right)$  

the following P-t data is plotted. (P = total pressure)

$\underset{\left(\min \right)}{\text{t}}$	0	20	$\infty$
$\underset{\left(\text{mm}\right)}{\text{P}}$	100	220	250

Calculate ${\text{t}}_{{ }^{\frac{24}{25}}}$ (time taken for $\frac{24}{25}\text{th}$ of the reactant to decompose) in minutes.