Please provide the formula

Determine costs from February to December if the monthly cost decreasing rate is 3% for Product A and 4% for Product B, using the cell locking function.
You are allowed to create ONLY one formula in cell B10, and apply this formula to all the remaining cells for Product A and Product B
		Product A	Product B
Monthly decreasing Rate	3.0%	4.0%
	Product A	Product B
January	$ 2,000	$ 3,500
February
March
April
May
June
July
August
September
October
November
December

Please describe the steps used to solve the problem

The client gives you the below table of their monthly Revenue and COGS; however, you noticed the revenue and COGS signs are inverted.
Using the Paste Special multiply feature, change the sign of the table below.
		January	February	March	April	May	June	July	August	September
Revenue	-$175,690	-$119,998	-$92,222	-$234,550	-$78,376	-$568,421	-$123,589	-$95,486	-$248,932
COGS	$123,809	$69,679	$64,810	$157,149	$52,512	$215,455	$63,258	$47,871	$101,210
Gross Profit	-$60,981	-$34,319	-$31,922	-$77,402	-$25,864	-$25,864	-$25,864	-$25,864	-$25,864