The expression in the image is:

$(7 \times 10^2) \times (3 \times 10^1)$

We will solve this step-by-step and express the result in scientific notation.

Step 1: Multiply the coefficients

First, multiply the numbers $7$ and $3$: $7 \times 3 = 21$

Step 2: Add the exponents

Next, add the exponents of $10$: $10^2 \times 10^1 = 10^{2+1} = 10^3$

Step 3: Combine the results

Now, combine the result from Step 1 and Step 2: $21 \times 10^3$

Thus, the final answer in scientific notation is: $2.1 \times 10^4$

Would you like further details on scientific notation, or do you have any questions?

Here are 5 related questions to extend your understanding:

1. How would you express $(5 \times 10^3) \times (2 \times 10^2)$ in scientific notation?
2. How do you handle division in scientific notation, such as $(8 \times 10^4) \div (4 \times 10^2)$?
3. How can you convert a large number like 5,600,000 into scientific notation?
4. What is the significance of the exponent when numbers are written in scientific notation?
5. How would you express a very small number, like 0.00034, in scientific notation?

Tip: When multiplying numbers in scientific notation, remember to add the exponents of 10, and then adjust the result to proper scientific notation.