A bicycle and a tricycle manufacturer makes bikes and trikes with the same size of wheels. They received a shipment of 100 wheels and they must use them all. How many bikes and trikes can they make?

2 trikes (6 wheels) and 47 bikes (94 wheels)

or

4 trikes (12 wheels) and 44 bikes (88 wheels)

or

6 trikes (18 wheels) and 41 bikes (82 wheels)

or

8 trikes (24 wheels) and 38 bikes (76 wheels)

or

10 trikes (30 wheels) and 35 bikes (70 wheels)

As long as you start our with an even number of trikes, you'll find a way to use up all the tires with no remainders.