Answer
$$Q_2= \frac{Q}{P}+Q_1 .$$
Work Step by Step
To solve the given equation for $Q_2$, we simplify as follows:
$$ Q_1=P(Q_2-Q_1)\Longrightarrow Q_1=PQ_2-PQ_1 \\ \Longrightarrow PQ_2= Q+PQ_1 \\ \Longrightarrow Q_2= \frac{Q+PQ_1}{P}\\ \Longrightarrow Q_2= \frac{Q}{P}+Q_1 .$$
