Forty-three race cars started in the Darlington -500 race. In how many way can a first, second and third place winner be determined

How to do this , and can some one explain

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Awater truck is filling a swimming pool. the equation that represents this relationship is y=19.75x where y is the number of gallons of water in the pool and x is the number of minutes the truck has been filling the pool.