The answer for number 4 is 13 and number 6 is 121 and the last problem for number 7 is 112
This is the Pythagorean theorem where the 2 legs of a triangle squared add up to equal the squared hypotenuse (a^2 + b^2 = c^2)
The equation would be
12^2 + 5^2 = x^2
144 + 25 = 169
The square root of 169 = 13
Answer - 13 ft
Haha, you first start off with adding 3 to both sides, cancelling the -3, and adding it to 9. you end up with 5x=12, in which you divide both sides by 5. you get 2 and 2/5 or 12/5! hope that helps :)