To solve the expression \( 7 \times 10^{3} - 8.20 \times 10^{10} \), you first need to ensure the terms are in the same power of ten. Since \( 10^{10} \) is much larger than \( 10^{3} \), it's easiest to express \( 7 \times 10^{3} \) in terms of \( 10^{10} \).
Convert \( 7 \times 10^{3} \) to have the same exponent as \( 10^{10} \):
\[ 7 \times 10^{3} = 7 \times 10^{3} \times \frac{10^{7}}{10^{7}} = 7 \times 10^{10} \times 10^{-7} = 0.0007 \times 10^{10} \]
Now, rewrite the original expression: \[ 0.0007 \times 10^{10} - 8.20 \times 10^{10} \]
Both terms can now be combined: \[ (0.0007 - 8.20) \times 10^{10} = (-8.1993) \times 10^{10} \]
So, the final result is: \[ -8.1993 \times 10^{10} \]