Multiply the capacity of the restaurant by 4/9. Remember any whole number can be made into a fraction by putting a 1 in the denominator.
270/1 x 4/9. When multiplying frations, multiply the numerators together and multiply the denominators together.
So, 270/1 x 4/9 = 1080/9. Now you can reduce the fraction, 1080/9 = 120. There are 120 people in the restaurant.