Let f be a differentiable function such that f(9)=18 and fâ²(9)=7. If g is the function defined by g(x)=f(x)xâ, what is the value of gâ²(9) ?.

Problem number 26 of the rhind papyrus says: find a quantity such that when it is added to of itself the result is a 15. the modern day equation that models this problem is x + x = 15. what is the solution to the equation? x = 10 x = 12 x = 15 x = 30