The number of cars in the yard is three times as high as the number of mopeds. The number of bicycles is twice as high as the number of cars. The total number of vehicles is 30. Use the equation to solve the number of cars, mopeds and bicycles.

Let the number of mopeds be x

number of cars will be 3*x=3x

number of bicycles will be 2*3x=6x

Total number=number of mopes+number of cars+number of bicycles

=x+3x+6x=30

10x=30

x=3

hence the number of mopeds was 3, number of cars was 3*3=9, number of bicycle was 2*9=18