# Tutor profile: Eric T.

## Questions

### Subject: SAT

Alex is staying at a hotel that charges $114.99 per night plus tax for a room. A tax of 8.25% is applied to the room rate, and an additional onetime service fee of $15.00 is charged by the hotel. Write an equation which denotes the total charge Alex will pay for staying "x" nights.

Similar to the question above, we'll denote the number of nights by x. As the nightly charge of $114.99 is applied each night, we'll simplify that to be 114.99x. The question now states a tax rate of 8.25% is applied to the room rate, and a onetime service fee of $15 is applied as well. Since the tax rate is only applied to the room rate, and not the service fee, it is key to only multiply 114.99x, the room rate, by the tax rate. To do this, enclose 114.99x in parentheses and multiply the number in parenthesis by 1.0825. It is important to multiply 114.99x by 1.0825, and not 0.0825, as taxes are applied on top of the current charge. You can then add 15 to the end of the equation as the additional service charge. Our equation is now 1.0825(114.99x) + 15, which is the correct answer.

### Subject: Biology

What is the order of biological classification, and how does this help biologists today?

Biological classification, also known as taxonomy, is how biologists today group and differentiate organisms. This is very useful in classifying organisms that share similar traits under a category, such as all amphibians (animals which can live on land or water) are under class Amphibia. The order of biological classification is: Kingdom, Phylum, Class, Order, Family, Genus, Species. This can be easily remembered by the mnemonic, "King Phillip Came Over For Good Spaghetti".

### Subject: Algebra

If a mystery number is first multiplied by 4, then 1 is subtracted, and this result is multiplied by 2, the answer is 22. What is the mystery number?

The key to the question is to simply the question in a work-able equation. We'll denote the mystery number as "x". If "x" is multiplied by 4, we can denote it as 4x. As 1 is subtracted from x, we can now expand the equation to be 4x-1. Since 4x-1 is multiplied by 2, it is important to close this part in parentheses to be (4x-1), and then multiple this part by 2. This can be denoted by 2(4x-1). The question now states this entire result is equal to 22, which we can write in as 2(4x-1) = 22. Using the distributive property, we will multiply each part of (4x-1) by 2, in which we will get 8x-2=22. To clean up the equation, we'll add 2 to both sides of the equation, to cancel the -2 on the left side. We then will arrive at 8x=24. We'll divide both sides by 8, to get x by itself. We then get x=3, which is the mystery number.

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