A. If a pipe can fill a tank in x hours. the part filled in 1 hour is 1/1+X
B. If a pipe can empty a full tank in y hours, the part emptied in 1 hour is 1/y
C. If a pipe can fill a tank in x hours and another pipe can empty the full tank in y hours (where y > x), then an opening both the pipes, the net part filled in 1 hour = 1/x - 1/y
Choose the correct statements from above: