Over 4 years, there will be a loss of 60,000 acres per year, so 60,000 times 4 is equal to 240,000 acres. 240,000 is positive because the problem asks for the change, not the increase.
This is the work you will show
c=-60,000(4)
c=-240,000
So -240,000 represents the change.
You could also just count by -60,000 four times.
-60,000-60,000-60,000-60,000=-240,000.
