To solve \( 0.078 - (5.2 \times 10^{-2}) \), let's first convert \( 0.078 \) to scientific notation.
The number \( 0.078 \) can be expressed as: \[ 0.078 = 7.8 \times 10^{-2} \]
Now we can perform the subtraction: \[ 7.8 \times 10^{-2} - 5.2 \times 10^{-2} \]
Since both terms are already in the same power of ten, we can combine them: \[ (7.8 - 5.2) \times 10^{-2} = 2.6 \times 10^{-2} \]
Thus, the final answer, expressed in scientific notation, is: \[ \boxed{2.6 \times 10^{-2}} \]