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 = \( \frac{80mi}{20mph} \)
4 hours

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so add the coefficients and retain the base and exponent:

-4x⁴ + 5x⁴
(-4 + 5)x⁴
x⁴

The absolute value is the positive magnitude of a particular number or variable and is indicated by two vertical lines: \(\left|-5\right| = 5\). In the case of a variable absolute value (\(\left|a\right| = 5\)) the value of a can be either positive or negative (a = -5 or a = 5).

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

2\( \sqrt{50} \) + 5\( \sqrt{2} \)
2\( \sqrt{25 \times 2} \) + 5\( \sqrt{2} \)
2\( \sqrt{5^2 \times 2} \) + 5\( \sqrt{2} \)
(2)(5)\( \sqrt{2} \) + 5\( \sqrt{2} \)
10\( \sqrt{2} \) + 5\( \sqrt{2} \)

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

To multiply terms with exponents, the base of both exponents must be the same. In this case they are so multiply the coefficients and add the exponents:

-5x⁶ x x⁴
(-5 x 1)x^{(6 + 4)}
-5x¹⁰