Answer:
3/4 is the answer
Explanation:
Steps to simplifying fractions
Find the GCD (or HCF) of numerator and denominator
GCD of 21 and 28 is 7
Divide both the numerator and denominator by the GCD
21 ÷ 7
28 ÷ 7
Reduced fraction:
3
4
Therefore, 21/28 simplified to lowest terms is 3/4.