## Math Review

Use Fractions

A fraction compares a part to a whole. In the fraction ——, the 2 represents the part and is the numerator. The 3 represents the whole and is the denominator.

Reduce Fractions To reduce a fraction, you must find the largest factor that is common to both the numerator and the denominator, the greatest common factor (GCF). Divide both numbers by the GCF. The fraction has then been reduced, or it is in its simplest form.

Example Twelve of the 20 chemicals in the science lab are in powder form.What fraction of the chemicals used in the lab are in powder form?

Step 2 To find the GCF of the numerator and denominator, list all of the factors of each number. Factors of 12:1,2,3,4,6,12 (the numbers that divide evenly into 12) Factors of 20:1,2,4,5,10,20 (the numbers that divide evenly into 20)

Step 3 List the common factors. 1,2,4.

Step 4 Choose the greatest factor in the list. The GCF of 12 and 20 is 4.

Step 5 Divide the numerator and denominator by the GCF.

In the lab, —— of the chemicals are in powder form.

Practice Problem At an amusement park, 66 of 90 rides have a height restriction.What fraction of the rides, in its simplest form, has a height restriction?

Add and Subtract Fractions To add or subtract fractions with the same denominator, add or subtract the numerators and write the sum or difference over the denominator. After finding the sum or difference, find the simplest form for your fraction.

Example 1 In the forest outside your house, - of the

animals are rabbits, —— are squirrels, and the remainder o are birds and insects. How many are mammals?