Find the L.C.D. of the following group of fractions and express in terms of the L.C.D.

Question

1/3, 3/5, 21/25,13/15
Puzzle!

Answer 1

3 = 3
5 = 5
25 = 5*5
15 = 3*5
so we need two fives and one three
5*5*3 = 75

Answer 2

There are several ways to approach this problem. I like finding the multiples of the largest number and then finding the one that all of the denominators will go into.

Example:
25, 50, 75, 100, 125

Answer 3

1/3 = ?/75
25/75

3/5 = ?/75
multiply top and bottom by 15
45/75

21/25 = ?/75
top and bottom by 3
63/75

13/15 = ?/75
top and bottom by 5
13*5 = 65
65/75