To calculate \( 0.078 - (5.2 \times 10^{-3}) \), we first need to express \( 0.078 \) in scientific notation.
The number \( 0.078 \) can be expressed as:
\[
0.078 = 7.8 \times 10^{-2}
\]
Now, we can rewrite the equation:
\[
7.8 \times 10^{-2} - 5.2 \times 10^{-3}
\]
Next, we need to express both terms with the same exponent. We can convert \( 5.2 \times 10^{-3} \) to the same power of ten as \( 10^{-2} \):
\[
5.2 \times 10^{-3} = 0.052 \times 10^{-2}
\]
Now the equation looks like this:
\[
7.8 \times 10^{-2} - 0.052 \times 10^{-2}
\]
Now, we can perform the subtraction:
\[
(7.8 - 0.052) \times 10^{-2} = 7.748 \times 10^{-2}
\]
Now that we have our result, we express it in scientific notation:
\[
7.748 \times 10^{-2}
\]
Thus, the final answer is:
\[
\boxed{7.748 \times 10^{-2}}
\]