What is x when 51 divided by x equals 7?

To find the answer, just divide the dividend by the quotient: 51 ÷ 7 = 7.2857142857143

To prove this, let's compute 51 divided by 7.2857142857143: $\frac{51}{7.2857142857143} = 7$

How does it work?

Asking what the value of x could be when 51 divided by x gives a result of 7, is equivalent to solving the following equation:

$\frac{51}{x} = 7$

Multiply both sides by x: $\frac{51 x}{x} = 7 x$
$\frac{51 x}{x}$ is equivalent to $\frac{x}{x} \times 51$ , which simplifies to $1 \times 51$ (or just $51$ ).
Thus, the equation becomes: $51 = 7 x$
To find x, divide both sides by 7: $\frac{51}{7} = \frac{7 x}{7}$
Which gives, after simplification: $7.2857142857143 = x$ (or $x = 7.2857142857143$ )

So, if the dividend is 51 and the quotient is 7, the divisor is 7.2857142857143.