Answer:
$43.60
Step-by-step explanation:
To calculate the total sale amount of a shirt, we need to add the sales tax to the selling price. The sales tax is calculated as 9% of the selling price. So, the sales tax is $40 * 0.09 = $3.60. Therefore, the total sale amount of the shirt is $40 (selling price) + $3.60 (sales tax) = $43.60.