What is a good trick for simplifying fractions?

Answer 1

Break each part of the fraction down into prime numbers and then remove the prime numbers that make up the greatest common factor. What you are left with is the reduced fraction.

10/30

10 = 1 x 2 x 5

30 = 1 x 2 x 3 x 5

GCF = 2 x 5 = 10

The greatest common factor numbers are 2 & 5; when these numbers are removed you are left with 1/3, which is 10/30 reduced.