Idon't seem to understand how to solve this one question, can anyone pease me out?

the answer is A. 25.0m³

you had 50.0 cubic meters at a temperature of 600k

then  its lowered to 300k which is half the number of 600k

so all you have to do is divide 50 by 2 which is 25

gravity causes stares to cluster i think so

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.