please be detailed and give formulas

Net Income Planning Holland Corporation earned an after-tax net income of $360,000 last year. Fixed costs were $1,800,000. The selling price per unit of its product was $120, of which $50 was a contribution to fixed cost and net income. The income tax date was 40%. a. How many units of product were sold last year? units b. What was the break-even point in units last year? units c. The company wishes to increase its after-tax net income by 20% this year. If selling prices and the income tax rate remain unchanged, how many units must be sold? units