I need some help with 3 and 4 thanks

Stratford Company distributes a lightweight lawn chair that sells for $30 per unit. Variable expenses are $9 per unit, and fixed expenses total $210,000 annually. Results for last year are as follows: Sales (18,000 units) 540,000 162,000 Variable expenses 378,000 Contribution margin 210,000 Fixed expenses 168,000 Operating income Nex