Solution:
Susan earns a commission based on car sales made.
Given:
Total sales made for the month = $387,000
Her commission is calculated based on levels and commision rate for each level.
On the first $100,000, she earns 1.25% commission.
Total sales at this level is $100,000
![\begin{gathered} \text{Commision made on the first \$100,000 is;} \\ \frac{1.25}{100}\times100000=\text{ \$1,250} \\ =\text{ \$1,250} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ctext%7BCommision%20made%20on%20the%20first%20%5C%24100%2C000%20is%3B%7D%20%5C%5C%20%5Cfrac%7B1.25%7D%7B100%7D%5Ctimes100000%3D%5Ctext%7B%20%5C%241%2C250%7D%20%5C%5C%20%3D%5Ctext%7B%20%5C%241%2C250%7D%20%5Cend%7Bgathered%7D)
On the next $200,000, she earns 4.95% commission.
Total sales at this level is $300,000
![\begin{gathered} \text{Commision made on the next \$200,000 is;} \\ \frac{4.95}{100}\times200000=\text{ \$9,900} \\ =\text{ \$9,900} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ctext%7BCommision%20made%20on%20the%20next%20%5C%24200%2C000%20is%3B%7D%20%5C%5C%20%5Cfrac%7B4.95%7D%7B100%7D%5Ctimes200000%3D%5Ctext%7B%20%5C%249%2C900%7D%20%5C%5C%20%3D%5Ctext%7B%20%5C%249%2C900%7D%20%5Cend%7Bgathered%7D)
On the next $87,000, total sales at this level is $387,000. She earns 7.25% commission for sales above $300,000.
![\begin{gathered} \text{Commision made on the next \$87,000 is;} \\ \frac{7.25}{100}\times87000=\text{ \$6,}307.50 \\ =\text{ \$6,}307.50 \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ctext%7BCommision%20made%20on%20the%20next%20%5C%2487%2C000%20is%3B%7D%20%5C%5C%20%5Cfrac%7B7.25%7D%7B100%7D%5Ctimes87000%3D%5Ctext%7B%20%5C%246%2C%7D307.50%20%5C%5C%20%3D%5Ctext%7B%20%5C%246%2C%7D307.50%20%5Cend%7Bgathered%7D)
Therefore, Susan's total commission received for the month is;
![\begin{gathered} \text{ \$1250 + \$9900 + \$6307.50} \\ =\text{ \$17,457.50} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20%5Ctext%7B%20%5C%241250%20%2B%20%5C%249900%20%2B%20%5C%246307.50%7D%20%5C%5C%20%3D%5Ctext%7B%20%5C%2417%2C457.50%7D%20%5Cend%7Bgathered%7D)
Hence, her commission received in total for the sales made is $17,457.50