Question

Which equation could you use to solve for x in the proportion 4/5=9/x ?

Answer 1

$\frac{9}{x} = \frac{4}{5}$
dividing both sides by 9
$\frac{1}{x} = \frac{4}{5 \times 9}$
rasing both sides to the power of -1
$x = \frac{5 \times 9}{4} = \frac{45}{4}$