A company's monthly sales, in thousands, is given by S(x, y) = 7x^0.4 y^0.5 where x is the amount spent on newspaper advertising per month in thousands of dollars and y is the amount spent on radio advertising per month in thousands of dollars. Suppose the company currently spends $4000 on newspaper advertising per month and $3000 on radio advertising per month. What would be the effect on sales if the company increases the amount spent on newspaper advertising to $5000, while the amount spent on radio advertising remains constant