Average speed in miles per hour is the number of miles traveled divided by the number of hours:

Solving for time:

time = \( \frac{\text{distance}}{\text{speed}} \)
time = \( \frac{225mi}{45mph} \)
5 hours

To divide fractions, invert the second fraction and then multiply:

\( \frac{3}{5} \) ÷ \( \frac{1}{7} \) = \( \frac{3}{5} \) x \( \frac{7}{1} \)

To multiply fractions, multiply the numerators together and then multiply the denominators together:

\( \frac{3}{5} \) x \( \frac{7}{1} \) = \( \frac{3 x 7}{5 x 1} \) = \( \frac{21}{5} \) = 4\(\frac{1}{5}\)

A rational number (or fraction) is represented as a ratio between two integers, a and b, and has the form \({a \over b}\) where a is the numerator and b is the denominator. An improper fraction (\({5 \over 3} \)) has a numerator with a greater absolute value than the denominator and can be converted into a mixed number (\(1 {2 \over 3} \)) which has a whole number part and a fractional part.

An integer is any whole number, including zero. An integer can be either positive or negative. Examples include -77, -1, 0, 55, 119.

To divide terms with radicals, divide the coefficients and radicands separately:

\( \frac{45\sqrt{14}}{9\sqrt{7}} \)
\( \frac{45}{9} \) \( \sqrt{\frac{14}{7}} \)
5 \( \sqrt{2} \)