# Tutor profile: Sarah J.

## Questions

### Subject: Pre-Algebra

Solve: 4/5-2/3=

Before we can solve this problem, we have to make the denominators the same so we can work with them. So, what's the smallest number that both denominators (5 and 3) will go into? That number would be 15. 4/5=?/15 (How many times will 5 go into 15? It goes 3 times, and 3 times 4 is 12, so we convert the first fraction to 12/15) and 2/3=?/15 (How many times will 3 go into 15? It does 5 times, and 5 times 2 is 10, so we convert the second fraction to 10/15) 12/15-10/15= The denominator will stay the same. We subtract 10 from 12, which leaves us with 2--that gives us 2/15. The answer is 2/15.

### Subject: Earth Science

What are the three main types of rocks, and how do we classify those rocks?

Rocks on Earth's surface are put into groups based on how they formed. Igneous: These rocks form when molten rock (lava or magma) cools and hardens. Sedimentary: These rocks form when small bits of minerals and older rocks cement together. Metamorphic: These rocks form when heat and/or pressure changes an old rock to a new rock.

### Subject: Algebra

Evaluate: 30 - 12÷3×2 =

We work this problem following the order of operations (PEMDAS), and we must keep in mind we are working left to right. When we are dividing or multiplying we work from left to right--and the same with adding or subtracting. P (parentheses) is the first operation to solve. This particular problem has none, so we move on to E (exponents). Again, this problem has none, so we move to multiplication and division. We complete all multiplication and division from left to right. 30 - 12 ÷ 3 × 2 = 30 - 4 × 2 = 30 - 8 = Now we work the last operations addition and subtraction. This problem only has subtraction, so: 30 - 8 = 22 22 is our answer.

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