[tex]\text{Hello there!}\\\\\text{Use the Pythagorean theorem first:}\\\\a^2+b^2=c^2\\\\\text{Plug 70 to c since it's your hypotenuse and plug 40 to a}\\\\40^2+b^2=70^2\\\\\text{Solve for b:}\\\\40^2+b^2=70^2\\\\1600+b^2=4900\\\\\text{Subtract 1600 from both sides}\\\\b^2=3300\\\\\text{Square root}\\\\b=57.4456\\\\\text{Round to the nearest tenth}\\\\57.4\\\\\text{Add 10 to 55.4 because the ladder is 10 ft off the ground}\\\\67.4\\\\\boxed{\text{Answer: about 67.4 ft}}[/tex]
