Exercise 5 Page 256

When adding or subtracting fractions, they should have the same denominator. In this exercise, we have two fractions with different denominators. 7 23 - 3 17 To create a common denominator, we will first find the least common denominator, LCD, of 3 and 7. To do it, we will write some multiples of 3 and 7 and find the smallest multiple that they both share. Multiples of3:& 3, 6, 9, 12, 15, 18, 21, 24, ... Multiples of7:& 7, 14, 21, 28, 35, 42, 49 ... We found that the LCD of 3 and 7 is 21. We can multiply both the numerator and denominator of 23 by 7 and the numerator and the denominator of 17 by 3 to create a common denominator.

Now that we have a common denominator, we can proceed to simplifying the expression.