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

2\( \sqrt{5} \) x 7\( \sqrt{4} \)
(2 x 7)\( \sqrt{5 \times 4} \)
14\( \sqrt{20} \)

Now we need to simplify the radical:

14\( \sqrt{20} \)
14\( \sqrt{5 \times 4} \)
14\( \sqrt{5 \times 2^2} \)
(14)(2)\( \sqrt{5} \)
28\( \sqrt{5} \)

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

\( \frac{2}{7} \) x \( \frac{2}{9} \) = \( \frac{2 x 2}{7 x 9} \) = \( \frac{4}{63} \) = \(\frac{4}{63}\)

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

Solving for distance:

distance = \( \text{speed} \times \text{time} \)
distance = \( 70mph \times 6h \)
420 miles

To simplify a radical, factor out the perfect squares:

\( \sqrt{27} \)
\( \sqrt{9 \times 3} \)
\( \sqrt{3^2 \times 3} \)
3\( \sqrt{3} \)

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{11 + 3 + 10 + 4}{4} \) = \( \frac{28}{4} \) = 7