What is the reason for using "letters" in algebraic problems? Why is such a thing needed?

Basic Algebra - Why Are There Letters in My Math??
Why Are There Letters?
Remember when you had math problems like this: 3 + = 10
This problem could be read, “Three plus something equals 10.”
Algebra uses letters to replace the . [ So the same problem can be written like this: 3 + x = 10
The problem could be read, “Three plus something equals 10.” or “Three plus x equals 10.” The “x” just stands

for “something”. We used x here, but we could use any letter. The letter is called the variable.
In algebra, our goal is to find out what number can replace the variable to make the equation true. In the example above, we know that 3 + 7 = 10. So the answer would be x = 7. (Replacing the x with a 7 makes the equation true.) ]

In a decimal number, the "hundreds place" is three places to the left of a decimal point. The "hundredths place" is two places to the right of a decimal point. So for the number 127.53, there is a 1 in the hundreds place and a 3 in the hundredths place. Therefore the "hundreds" represents a larger value.

Added 1/2/2015 7:37:57 AM

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