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 = \( \frac{100mi}{50mph} \)
2 hours

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

\( \frac{27\sqrt{15}}{9\sqrt{5}} \)
\( \frac{27}{9} \) \( \sqrt{\frac{15}{5}} \)
3 \( \sqrt{3} \)

To subtract these radicals together their radicands must be the same:

9\( \sqrt{75} \) - 8\( \sqrt{3} \)
9\( \sqrt{25 \times 3} \) - 8\( \sqrt{3} \)
9\( \sqrt{5^2 \times 3} \) - 8\( \sqrt{3} \)
(9)(5)\( \sqrt{3} \) - 8\( \sqrt{3} \)
45\( \sqrt{3} \) - 8\( \sqrt{3} \)

Now that the radicands are identical, you can subtract them:

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.

There are 4 4-passenger taxis available so that's 4 x 4 = 16 total seats. There are 20 people needing transportation leaving 20 - 16 = 4 who will have to find other transportation.