21 - 1/3 = 20 2/3
To solve this, you must first know 3/3 = 1. Therefore, you must subtract 1 from 21 to get 21, but add back in the 2/3 that is left over.

Domid

21 - 1/3
Convert 21 into an improper fraction
21/1 - 1/3
Multiply until both fractions have the same common denominator
63/3 - 1/3
Subtract the numerators but NOT the denominators
Final Answer: 62/3 or 20 2/3 *Both answers are equivalent to each other.