In a simple linear regression, we are using monthly advertising expenditures (in $000) to predict monthly profits

Question:

In a simple linear regression, we are using monthly advertising expenditures (in $000) to predict monthly profits (in $000). If the least squares equation is y = 21.5 - .1x and the coefficient of determination is .49. The increase in profit for each $1,000 increase in advertising expenditures = __________ is