so first we start off multiplying 3 • 7 to find a common denominator and you get 21. Then because you technically multiplied 3 by 7 you also have to multiply 1 by 7! you instead of 1/3 you have 7/21! do the similar thing to 2/7 but instead of multiplying it by 7 you use 3 so for this one instead of 2/7 it’s 6/21! add the two fractions together and get 13/21! subtract 13 from 21 to see what the remaining fraction is and your answer is 8/21! hope this helps!!
