The inverse of the function is k(x) = 

You can find the inverse of any function by switching the k(x) value and the x value. After that, solve for the new k(x). The result will be your inverse function. The step-by-step process is below. 
k(x) = 10x + 5 ----> Switch the x and k(x) 
x = 10k(x) + 5 ----> Subtract 5 from both sides
x - 5 = 10k(x) ----> Divide both sides by 10. 
 = k(x) ----> Now switch the order for formatting
k(x) = 

And this is your new inverse function.