What is the value of the number one in 61

Need ! give step by step solutions on how to solve number one \frac{9-2\sqrt{3} }{12+\sqrt{3} } number two x+4=\sqrt{13x-20} number three (domain and range) f(x)=2\sqrt[3]{x} +1

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

Cuántos triángulos forman un diamante