PROBLEM:

The North American and European continents are moving apart at a rate of about 3 cm/y. At this rate how long will it take them to drift 500 km farther apart than they are at present?

SOLUTION:

We know that the formula for velocity is

\text{velocity}=\frac{\text{displacement}}{\text{time}}

If we rearrange the formula and solve for time, we come up with

\text{time}=\frac{\text{displacement}}{\text{velocity}}

Substituting the given values,

\begin{align*}
\Delta \text{t} & =\frac{500\:\text{km}}{3\:\text{cm/year}} \\ \\
& =\frac{5\times 10^5\text{ m}}{3\:\text{cm/year}}\times \frac{100\:\text{cm}}{1\:\text{m}} \\ \\
& =1.67\times 10^7\text{years} \ \qquad \ \color{DarkOrange} \left( \text{Answer} \right) \\
\end{align*} 

Therefore, the time it will take is about 1.67\times 10^{7}\ \text{years}.