In the Wizard World, currency exchange is inconsistent. One Galleon from the Wizarding World is equivalent to $8.64 U.S. Dollars, while eleven Galleons is equivalent to $88.64. Write two conversion functions: one converting from Galleons to Dollars, and one from Dollars to Galleons.

A doctor receives two invoices for an order including gloves and masks. The first order cost $605 and included 2000 gloves and 500 masks while the second order of 10000 gloves and 600 masks cost $916 dollars. The invoice does not show the cost of the gloves or masks. Find the cost of each glove and of each mask.

A math course has two midterms and a final exam. Midterm 1 is worth 18% of the final grade, midterm 2 is worth 36% of the final grade, and the final exam is worth 46%. The teacher assigns grades as marks on 100. If a student recieved a mark of 78.1 on the first midterm and 72.6 on the second midterm, what mark does he need on the final exam to get a final grade of 80 in the course. Please use excel for all calculations. Give the answer to 5 decimal places.

Lamar works as a car audio technician. Last week a total of 27 cars came into his shop and he made a total of $3,049.73. If Lamar normally charges $99.99 for installation of a stereo and $149.99 for the installation of a speaker system, how many of each component did he install last week?