Answer
The revenue during the second year only was $\$300,000,000$.
Work Step by Step
From part (b), the total revenue the the end of the second year is $\$500,000,000$ while from part (b), the total revenue at the end of the first year is $\$200,000,000$.
The revenue during the second year only can be found by subtracting the total revenue at the end of the first year to the total revenue at the end of the second year.
Thus,
$\text{revenue during the second year only}
\\=\$500,000,000 - \$200,000,000
\\=\$300,000,000$
