To add fractions with different denominators, find a common multiple to multiply the denominators and numerators by so they match. Then simply add the numerators and keep the denominator the same. For example, to add 5/2 and 2/5, multiply the denominators by 2 and 5 respectively to get 10 as the common denominator. Multiply the numerators by the same numbers to get 10/10 + 10/10, then add the numerators to get 20/10 or 2.