please help me

Sandy and Dan jointly own a business, and they equally share the proceeds of the business. The revenue function of the business is 3xy+6y, where x and y represent the effort levels exerted by Sandy and Dan. The costs of effort for these people are x and y respectively. a. Draw the reaction functions of Sandy and Dan on the same graph and indicate clearly which is which. (10 points) b. Find out the Nash equilibrium and total profit, assuming decisions are taken simultaneously. (10 points)