2. What … (to happen) to our sales if we … (to increase) our advertising costs by 5%?

2. What … (will happen) to our sales if we … ( increase) our advertising costs by 5%? 2. What … ( happens) to our sales if we … ( increase) our advertising costs by 5%? 2. What … (would happen) to our sales if we … ( increased) our advertising costs by 5%? 2. What … (would have happened) to our sales if we … (had increased) our advertising costs by 5%?