You are selling a product for $$979$ per unit, have variable manufacturing costs of $$520$ per unit, variable selling expense of $$187$ per unit, fixed manufacturing costs of $$520,000,$ fixed selling expense of $$57,000,$ and fixed administrative costs of $$200,000.$

a$.$ How many units must you sell to break$-$even?

b$.$ How many units must you sell to earn a pretax profit of $$530,000?$