1996 AMC 8 第 5 题

From the number line, $P$ and $Q$ are negative while $R,$ $S,$ and $T$ are positive

A product or quotient is negative only with an odd number of negative factors; check each choice

From the number line, $P$ and $Q$ are negative and $R,$ $S,$ and $T$ are positive.

Then $P \cdot Q$ is positive; $\dfrac{S}{Q} \cdot P$ has two negative factors, so it is positive; $\dfrac{R}{P \cdot Q}$ is positive; and $\dfrac{S + T}{R}$ is positive. Since $P$ is to the left of $Q,$ $P - Q$ is negative.

Thus, the correct answer is A .