.9 is equal to 9/10, which is less than 1
when multiplying a number by a value less than one, the product will be smaller than the original number
multiply 30/1 * 9/10 by putting the product of the numerators over the product of the denominators --> 270/10. simplify to 27/1, or 27.
-or-
first find the GCF of 30 and 10 (10) and divide each value by this GCF (you can do this because they are diagonal when multiplying). this gives you 3/1 * 9/1 --> 27/1, or 27.
