Gas phase decomposition of Di-tert-butyl peroxide $(M{e}_{3}CO-OCM{e}_3)$ (DTBP) to acetone and ethane follows first order kinetics. The plot of log P vs time (t) is as given below. (P is pressure of DTBP in torr)

$M{e}_{3}COOCM{e}_3\left(g\right)\to 2MeCOMe\left(g\right)+C_2{H}_6\left(g\right)$
 

In one hour, the percentage dissociation of DTBP is found to be $\text{'}x\text{'}$ and the pressure of the system after one hour is found to be $\text{'}y\text{'}$ torr.