Find the Lowest Common Denominator (LCD) of all the denominators of the "little" fractions
Multiply the numerator and denominator of the "big" fraction by the LCD found in step #1.
Let's see how this works on your complex fractions. The "little" fractions are 1/2, 1/3 and 1/6. The LCD of 2, 3 and 6 is 6. So we will multiply the numerator and denominator of the "big" fraction by 6:
To multiply correctly we will need to use the Distributive Property in both the numerator and denominator:
Notice how all the "little" fractions disappear when you multiply by the LCD!
which simplifies to 1!