HELP! NEED EXPLANATION FOR UNDERSTANDING A STEP IN THIS EQUATION

I understand steps 1 and 2 but then in step 2 i don't see how the 6 and 3 cross out and form a 2

HELP NEED EXPLANATION FOR UNDERSTANDING A STEP IN THIS EQUATION I understand steps 1 and 2 but then in step 2 i dont see how the 6 and 3 cross out and form a 2 class=