The gross receipts would include the sales profit and the sales tax. We let sales profit be the variable x. The equation we can make from the word problem would be
Gross profit = x + 0.03x = $3554.53
The sales tax is taken as the percentage of the total sales profit. Solving for x,
1.03x = 3554.53
x = 3554.53/1.03
x = $3451
The sales tax is equal to
Sales tax = 0.03($3451) = $103.53