Correct Answer - `pi=((pi_(1)V_(1)+pi_(2)V_(2))/(V_(1)+V_(2)))`
`C_(t)=(C_(1)V_(1)+C_(2)V_(2))/(V_(1)+V_(2))`
`pi_(1)=C_(1)RT, C_(1)=((pi_(1))/(RT)) , pi_(2)=C_(2)RT, C_(2)=((pi_(2))/(RT))`
`pi=((C_(1)V_(1)+C_(2)V_(2))/(V_(1)+V_(2)))RT`
`pi=((pi_(1)V_(1)+pi_(2)V_(2))/(V_(1)+V_(2)))`