What is x when 15 divided by x equals 21?

In other words, what would the divisor be if the dividend were 15 and the quotient 21?

To find the answer, just divide the dividend by the quotient: 15 ÷ 21 = 0.71428571428571

To prove this, let's compute 15 divided by 0.71428571428571: 15 0.71428571428571 = 21

How does it work?

Asking what the value of x could be when 15 divided by x gives a result of 21, is equivalent to solving the following equation:

15 x = 21

  1. Multiply both sides by x: 15 x x = 21 x
  2. 15 x x is equivalent to x x × 15 , which simplifies to 1 × 15 (or just 15 ).
  3. Thus, the equation becomes: 15 = 21 x
  4. To find x, divide both sides by 21: 15 21 = 21 x 21
  5. Which gives, after simplification: 0.71428571428571 = x (or x = 0.71428571428571 )

So, if the dividend is 15 and the quotient is 21, the divisor is 0.71428571428571.