Answer:
x = 1/3
Explanation:
You are saying that the dividend (the number being divided) is unknown. Represent it by x:
x ÷ 5/7 = 7/15. Recall that dividing by 5/7 is the same as multiplying by 7/5, so that
x(7/5) = 7/15.
Here the LCD is 15. Thus, mult. numerator and denominator of 7x/5 by 3:
21x/15 = 7/15.
Then 21x = 7. Dividing both sides by 21 isolates x: x = 7/21, or x = 1/3.