Answer
(a) 1500
(b) 1625
Work Step by Step
a. Profit = UNIT CM * Q - Fixed expense
=> $10000=(120-80)Q - 50000$
=> $Q= \frac{60000}{40}=1500$ units
b. Sales in unit = (Target profit + Fixed cost) / (Price per unit - Variable cost per unit) = $\frac{15000 + 50000}{120-80}=1625$