liberal arts mathematics 12 grade

Question

Thrifty Parking Garage has 40 parking spaces. Each space can be used by a car or a motorcycle (no trucks). One day when all 40 spaces are in use, the owner walks through the garage and looks at each vehicle. He tells his assistant, "There are 152 wheels in this garage right now." How many motorcycles are in the garage?

Answer 1

Let x = number of cars

 

Then, 40-x = number of motorcycles

 

Each car has 4 wheels and each motorcycle has 2 wheels

 

So, 4x + 2(40-x) = 152

 

                   2x = 72

 

                     x = 36

 

There are 36 cars and 4 motorcycles in the parking garage.

 

Answer 2

If all parking places were occupied by 4-wheeled vehicles, there would be 40 automobiles and no motorcycles.

But this comes up 8 short, which means 4 motorcycles because each motorcycle has 2 wheels & the other 36 are cars.

 

Check 4 times 36 + 4 times 2 = ___ wheels.