Answer
$$\frac{-7}{x} - (\frac{-12}{x})$$
or
$$\frac{5}{x}$$
Work Step by Step
Let's look at this statement in pieces:
The "quotient of $-7$ and a number" can be translated to "$-7 \div x$ or $\frac{-7}{x}$".
The answer to this portion is then subtracted from "the quotient of $-12$ and the number," which can be translated to "$-12 \div x$ or $\frac{-12}{x}$".
So let us take the first expression and subtract it from the second expression:
$$\frac{-7}{x} - (\frac{-12}{x})$$
Since both fractions have the same denominator, then we can subtract the numerators and keep the same denominator. Remember that when we subtract a negative number, we actually add the additive inverse of that number instead:
$$\frac{-7}{x} + \frac{12}{x}$$
$$\frac{5}{x}$$