What is x when 78 divided by x equals 21?

In other words, what would the divisor be if the dividend were 78 and the quotient 21?

To find the answer, just divide the dividend by the quotient: 78 ÷ 21 = 3.7142857142857

To prove this, let's compute 78 divided by 3.7142857142857: 78 3.7142857142857 = 21

How does it work?

Asking what the value of x could be when 78 divided by x gives a result of 21, is equivalent to solving the following equation:

78 x = 21

  1. Multiply both sides by x: 78 x x = 21 x
  2. 78 x x is equivalent to x x × 78 , which simplifies to 1 × 78 (or just 78 ).
  3. Thus, the equation becomes: 78 = 21 x
  4. To find x, divide both sides by 21: 78 21 = 21 x 21
  5. Which gives, after simplification: 3.7142857142857 = x (or x = 3.7142857142857 )

So, if the dividend is 78 and the quotient is 21, the divisor is 3.7142857142857.