Explain how 9x4 can help you find 9x8?

In multiplication, we can apply the commutative property, this means that:

abc = acb

Now, we know that:

8 = 4 * 2

This means that:

9*8 = 9 * 4 * 2

This means that

9*8 is twice as much as 9*4 is 36, we can simply multiply this value by 2 to get 9*8

Therefore:

9 * 8 = 2 (9*4) = 2(36) = 72

Hope this helps :)