Rewrite the first number with the same exponent as the second number.

To subtract numbers in scientific notation, their exponents must be the same. We will convert $3 \times 10^{-5}$ to have an exponent of $-3$.

Now that both numbers have the same exponent ($10^{-3}$), we can subtract their coefficients.

So the expression becomes:

A number is in standard scientific notation when it is written as $a \times 10^b$, where $1 \le |a| < 10$ and $b$ is an integer. In our result, $-7.97$ satisfies $1 \le |-7.97| < 10$.