Answer:
There are 7 motorcycles and 13 cars.
Step-by-step explanation:
If M is the number of motorcycles, and C is the number of cars, then:
M + C = 20
2M + 4C = 66
Solve with elimination. Multiply the first equation by 4, then subtract the second equation.
4M + 4C = 80
2M = 14
M = 7
C = 13
There are 7 motorcycles and 13 cars.