no problem akhila  If an applicant has scored: Physics 90 (theory 50, practical 40; max. marks theory 60, practical 40), 

and Chemistry 91(theory 52, practical 39; max. marks theory 60, practical 40) which is not in ratio of 

70: 30, then the marks can be converted on pro rata basis

Pro rata marks in physics = 88.33; ((50/60) x 70 + (40/40) x 30) = 58.33 + 30 = 88.33

Pro rata marks in chemistry = 89.92; ((52/60) x 70 + (39/40) x 30) = 60.66 + 29.25 = 89.91