Please provide explanation and equations used so that I can answer similar questions, thank you.

Sally Crane, sales manager for ISG, Inc. believes that if she increases advertising spending by $5,000, they will sell 100 more units. The current selling price is $450 per unit with a variable cost of $300 per unit. What will the impact of this decision have on operating income? Decrease of $10,000 Increase of $10,000 o o Decrease of $15,000 More information is needed to answer this