So we know that 3/4 is equivalent to 9/12, because 3×12=36 and 4×9=36. A simple way to look at how to check for equivalent fractions is to do what is called “cross-multiply”, which means multiple the numerator of one fraction by the denominator of the other fraction. Then do the same thing in reverse.
ANSWER:To determine if all three of those fractions have the same decimal equivalent, we simply divide the numerator by the denominator. Fractions mean division! So for the first one 21/3 That's 21 divided by 3. That's 7!