What is x when 51 divided by x equals 87?

To find the answer, just divide the dividend by the quotient: 51 ÷ 87 = 0.58620689655172

To prove this, let's compute 51 divided by 0.58620689655172: $\frac{51}{0.58620689655172} = 87$

How does it work?

Asking what the value of x could be when 51 divided by x gives a result of 87, is equivalent to solving the following equation:

$\frac{51}{x} = 87$

Multiply both sides by x: $\frac{51 x}{x} = 87 x$
$\frac{51 x}{x}$ is equivalent to $\frac{x}{x} \times 51$ , which simplifies to $1 \times 51$ (or just $51$ ).
Thus, the equation becomes: $51 = 87 x$
To find x, divide both sides by 87: $\frac{51}{87} = \frac{87 x}{87}$
Which gives, after simplification: $0.58620689655172 = x$ (or $x = 0.58620689655172$ )

So, if the dividend is 51 and the quotient is 87, the divisor is 0.58620689655172.