A number in scientific notation has the format 0.000 x 10^exponent. To convert to scientific notation, move the decimal point to the right or the left until the number is a decimal between 1 and 10. The exponent of the 10 is the number of places you moved the decimal point and is positive if you moved the decimal point to the left and negative if you moved it to the right:

0.0003903 in scientific notation is 3.903 x 10^-4

There are 3 3-passenger taxis available so that's 3 x 3 = 9 total seats. There are 13 people needing transportation leaving 13 - 9 = 4 who will have to find other transportation.

The least common multiple (LCM) is the smallest positive integer that is a multiple of two or more integers.

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

6\( \sqrt{80} \) + 7\( \sqrt{5} \)
6\( \sqrt{16 \times 5} \) + 7\( \sqrt{5} \)
6\( \sqrt{4^2 \times 5} \) + 7\( \sqrt{5} \)
(6)(4)\( \sqrt{5} \) + 7\( \sqrt{5} \)
24\( \sqrt{5} \) + 7\( \sqrt{5} \)

Now that the radicands are identical, you can add them together:

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

\( \frac{4}{9} \) ÷ \( \frac{2}{9} \) = \( \frac{4}{9} \) x \( \frac{9}{2} \)

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

\( \frac{4}{9} \) x \( \frac{9}{2} \) = \( \frac{4 x 9}{9 x 2} \) = \( \frac{36}{18} \) = 2