4.12. Preparation for bringing fractions with different denominators to a common denominator

We learn all 3 types of bringing fractions with different denominators to a common denominator. In this material, the internal arithmetic structure of the denominators is still visible, so we can understand how we form the common denominator from the factors in the denominators for each of the 3 types, and why. We can also understand how to expand each fraction to reach the common denominator.