Question

(A) 80m (B) 60m (C) 150m (D) 20m (E) 40m

Answer 1

$a^{2} =b^{2} + c^{2} \\100^{2} = x^{2} + 60^{2} \\10000 = x^{2} + 3600\\\x^{2} = 10000 - 3600\\x^{2} = 6400\\x = \sqrt{6400} \\x = 80$