How do you solve $\frac{3}{10}=\frac{9}{y}$ ?

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Answer 1 · 2017-07-30T22:46:03

See a solution process below:

First, we can "flip" each fraction:

$3/10 = 9/y$ becomes:

$10/3 = y/9$

Now, multiply each side of the equation by $color(red)(9)$ to solve for $y$ while keeping the equation balanced:

$color(red)(9) xx 10/3 = color(red)(9) xx y/9$

$cancel(color(red)(9))3 xx 10/color(red)(cancel(color(black)(3))) = cancel(color(red)(9)) xx y/color(red)(cancel(color(black)(9)))$

$3 xx 10 = y$

$30 = y$

$y = 30$

Answer 2 · 2017-07-30T22:47:30

Use cross-multiplication. $y=30$

Cross-multiply the denominator on each side with the numerator on the other side:
$3 * y=9*10$
$3y=90$
Divide by 3:
$y=30$

How do you solve \frac{3}{10}=\frac{9}{y}\frac{3}{10}=\frac{9}{y}?