How do you solve $\frac { 5} { x } = \frac { 3} { x - 12}$ ?

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Answer 1 · 2017-07-16T17:21:36

$x = 30$

When you have an equation where the variable is on the denominator on both sides, cross-multiplication would be the way to go.

Multiplying both sides by $x(x-12)$ (the common multiple)
$(5(x-12))/(x(x-12))=(3x)/(x(x-12))$

you can then cancel out the common denominator, leaving you with:
$5(x-12)=3x$

Distributing...
$5x-60=3x$

Subtracting $3x$ from both sides
$2x - 60 = 0$

Adding 60 to both sides...
$2x = 60$

Finally dividing both sides by $2$ ...
$x = 60/2 = 30$

Therefore, $x = 30$

How do you solve \frac { 5} { x } = \frac { 3} { x - 12}\frac { 5} { x } = \frac { 3} { x - 12}?