Which phrase best defines the liquidity of money?

When the federal reserve buys bonds from or sells bonds to member banks, it is called monetary policy reserve ratio interest rate adjustment open market operations

Alarge tank is filled to capacity with 500 gallons of pure water. brine containing 2 pounds of salt per gallon is pumped into the tank at a rate of 5 gal/min. the well-mixed solution is pumped out at the same rate. find the number a(t) of pounds of salt in the tank at time t.

The owner of firewood to go is considering buying a hydraulic wood splitter which sells for $50,000. he figures it will cost an additional $100 per cord to purchase and split wood with this machine, while he can sell each cord of split wood for $125. if, for this machine, design capacity is 50 cords per day, effective capacity is 40 cords per day, and actual output is expected to be 32 cords per day, what would be its efficiency?