Ali has a 10 ft piece of pipe that she needs to cut down. She cuts off and she cuts
1
1
5
3
off and .
Evaluate the following expression to determine how much pipe she has cut off in
total:
1 1
+
5 3
Solution/Explanation:
The fractions have unlike denominators. First, find the Least Common
Denominator and rewrite the fractions with the common denominator.
1 1
LCD ( , ) =15
5 3
Multiply both the numerator and denominator of each fraction by the number that
makes its denominator equal the LCD. This is basically multiplying each fraction
by 1.
1 1
1 5
( × ) + ( × ) =?
5 3
3 5
Complete the multiplication and the equation becomes
3 5
+ =?
15 15
The two fractions now have like denominators so you can add the numerators.
Then:
3+5 8
=
15 15
This fraction cannot be reduced.
Therefore:
1 1 8
+ =
5 3 15