Answer:
10/21
Explanation:
First, you have to find the common denominator! In this equation, 7 is divisible by 21! This means that we could multiply the 7 by 3. If we have to multiply the denominator, we also have to multiply the numerator! This means that it would be 3/21. Final step! 13/21 - 3/21 = 10/21
I hope this helps! :)