Find 5- (-7) write as addition

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 value of x in the diagram below?

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)