# Tutor profile: Elizabeth L.

## Questions

### Subject: Pre-Algebra

Evaluate using the values given: 8(x − y); use x = 5, and y = 2

In this problem, we are given an x and y value. We can use these values to plug into the equation. Since x=5, we will substitute 5 for the x in 8(x-y). Since y=2, we will substitute the y in 8(x-y). Our equation will now look like the one below. 8(5-2) Using order of operations (PEMDAS), we will deal with the numbers in parenthesis first (5-2, which equals 3. Our equation will now look like the one below. 8(3) Multiplying, we now get 8*3=24 Our answer is 24! :)

### Subject: Basic Math

Select the numbers that are prime. 2 5 8 13

A prime number is a number that can only be divided by 2 numbers (1 and itself) without a remainder. Some facts about prime numbers include: The only even prime number is 2. All other even numbers can be divided by 2. If the sum of a number's digits is a multiple of 3, that number can be divided by 3. No prime number greater than 5 ends in a 5. Any number greater than 5 that ends in a 5 can be divided by 5. Zero and 1 are not considered prime numbers. Now, let's look at the problem at hand. From the facts listed above, we can rule that 2 and 5 are prime numbers. Now let's look at 8. What numbers can be divided into 8 without remainders? 1, 2, 4, 8. That's more than just 1 and 8, so 8 is not a prime number. Now let's look at 13. What numbers can be divided into 13 without remainders? 1 and 13. That means 13 is a prime number. 2, 5, 13 are the prime numbers from those listed :)

### Subject: Algebra

Solve the equation: -5x + 20 = 25

In this problem, we are trying to solve for x. We need to get x on one side of the equation by itself. Now, what's the first thing that we can do to the left side to try and get the x by itself? That's right! Let's work on that +20. Since it is being added, we need to do the opposite operation on both sides. Below, the equation is now rewritten to show -20 on both sides and simplified. -5x+20-20=25-20 -5x=5 Now that we have the +20 out of the way, let's work on that -5. Since the -5 is being multiplied in this case, we will need to do the opposite operation on both sides. We will divide both sides of the equation by -5 as shown below. -5x/-5=5/-5 x=-1 And that's it! x=1 :)

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