1.the car catches the bus 10 hrs after it (the car) leaves i.e. 12 hrs after the bus leaves phoenix. in 12 hrs, the bus travels a distance 540 miles (45miles/hr*12hrs). that means the car travels 540 miles in 10 hrs. therefore, its speed is 540/10=54miles/hr.2.the salt is 30% in 20 gallons. i.e. it is [(30/100)*20] gallons.it comes out to be 6 gallons. for it to be 45%, [(45/100)*x]=6 gallons. where x is the total amount of solution left after evaporating. on calculating, x comes out as 13.33. hence, amount of water that can be evaporated so as to keep the solution less than 45% is less than 6.66 gallons
