7.04 Commission based earnings, piecework, royalties

Calculate the amount of commission a salesperson will receive if they earn $5%$5% on sales and the amount they sold was $\$8000$$8000.

If a commission of $20%$20% is paid on all sales, what is the total value of sales if the gross income is $\$238$$238?

Han is paid a commission of $3%$3% of the value of trucks sold in excess of $\$2100$$2100. Calculate his income if he sells trucks to the value of $\$6600$$6600.