Charges for filing each tax return not through the easiest form = $35
Charges for the filing each tax return through the easiest form = $0
Donation made to clean water project for each tax return filed = $2
Let total tax returns filed be 'a' and total tax returns filed at $35 be 'b'
⇒ Tax returns filed at $0 = a-b
Total money charged by Sterre = $7, 245
Total donation made by Sterre = $1, 242
Now, first we will determine the total tax returns filed by Sterre
Total donation made by Sterre = Donation made per tax return × Total returns filed by Sterre
⇒ 1,242 = 2 × a
⇒ a = 621
Hence, Sterre filed total of 621 tax returns
Now total money charged by Sterre = Charges for filing each tax return not through the easiest form × Tax returns filed at $35
⇒ 7,245 = 35 * b
⇒ b = 207
Hence, Sterre filed 207 returns at $35.
⇒ Tax returns filed at $0 = 621 - 207
⇒ Tax returns filed at $0 = 414
Hence, at $35, Sterre filed 207 tax returns, and at $0 Sterre filed 414 tax returns.
