# How do you solve 3.4/x=2.17/7.7?

Aug 12, 2016

x = 12.06

#### Explanation:

Multiply both sides by 7.7 to remove it on the right side of the equation:

$7.7 \times \frac{3.4}{x} = \frac{2.17}{\cancel{7.7}} \times \cancel{7.7}$

Multiply 7.7 and 3.4 together to get a value of 26.18:

$\frac{26.18}{x} = 2.17$

Divide 26.18 by 2.17 to get x by itself:

$\frac{26.18}{2.17} = x$

$x = 12.06$

Aug 12, 2016

$x \approx 12$

#### Explanation:

Solve for $x$: $\frac{3.4}{x} = \frac{2.17}{7.7}$

Cross multiply.

$3.4 \times 7.7 = 2.17 x$

Simplify.

$26.18 = 2.17 x$

Divide both sides by $2.17$.

$\frac{26.18}{2.17} = \frac{\cancel{2.17} x}{\cancel{2.17}}$

$12.064516129032 = x$

Switch sides.

$x = 12.064516129032 \approx 12$ (rounded to two significant figures, or round to the number of digits your instructor requires)

Aug 12, 2016

There's another way to do this that doesn't require cross-multiplying.

Reciprocate both sides:

$\frac{3.4}{x} = \frac{2.17}{7.7}$

$\to \frac{x}{3.4} = \frac{7.7}{2.17}$

Now simply multiply by $3.4$ on both sides to get $x$.

$\textcolor{b l u e}{x} = \frac{3.4 \cdot 7.7}{2.17}$

$\approx \textcolor{b l u e}{12.06}$