This tutorial reviews how to use cancellation when multiplying fractions.

Examine the example 9/10 x 5/12.

Switching the numerators would not change the answer.

We can switch the 5 and 9.

Now we have the problem 5/10 x 9/12.

Both fractions can be reduced.

5/10 = 1/2 and 9/12 = 3/4

Multiply the reduced fractions together.

1/2 x 3/4 = 3/8

This is basically the same thing as using cancellation.