please answer these multiple choices related to advanced mathmatics in chemical engineering.

In a closed system made of two tanks, with equal volumes, initially the first tank contains fresh water and the second tank contains brine with 100 kg of salt after long time of mixing each tank will contain Select one: O a. 100 kg salt O b. 75 kg salt O c. 50 kg salt A system of tanks in transient is modelled by Select one: O a. a system of algebraic equations O b. a single ODE O c. a system of ODES