1/2 belongs to what family of real numbers

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

What is the rotational symmetry of a wheel

What is the missing step in this proof ?