Please explain how this was combined to see that k=(8/5)*L? please explain this step by step, thanks !

A firm's production function is Q = K 05L0\". The rm is perfectly competitive and hires its machines at a constant rental rate of r = 5 and its workers at a constant wage rate of w = 4. It can sell as much output as it wishes at the market price of P = 40. a. Find the most protable output, the prots at his output, and the capital and labour inputs. b. How would the most protable output change if price rose to 60. What does this tell us about the firm's supply function? Does it appear to be elastic or inelastic?