Royce sells custom knitted scarves for $45. His variable cost is $10 per scarf and fixed costs are $300 per month. He is currently selling 50 scarves each month. Royce thinks that if he spends $500 in advertising, his sales will increase by 40 scarves each month. How will this impact Royce's operating income? O increase of $1000 O decrease of $900 O decrease of $1000 increase of $900