## Elementary Algebra

$b = 2\sqrt21$ yards
Plugging in given values into the Pythagorean Theorem gives: $4^2 +b^2 = 10^2$ Simplify by subtracting $4^2$ from both sides: $b^2 = 10^2-4^2 = 100-16 = 84$ To Simplify $b^2 = 84$, take the square root of both sides: $\sqrt b^2 = \sqrt 84 = \sqrt {4 \times 21}$ Finally, simplifying the radical gives the answer: $b = 2\sqrt21$ yards