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 How to write algebraic expressions In mathematics, algebra is where we use letters or symbols to represent unknown numbers Variable: A variable is a symbol, usually a letter used to represent a number. Any letter may be used as a variable. We use algebra to translate words into mathematics. For example suppose we use the variable n to represent any unknown number we do not know in the following sentences.         1) a number plus 3 becomes                                     n + 3         2) four times a number becomes                               4n         3) three less than a number becomes                       n-3         4) eight more than a number becomes                      8 + n         5) Sally is four times as old as James less three years             In the above problem we let                       n=James’s age so                                                                           4n-3=Sally’s age To write multiplication using variables always put the multiplier (number) before the variable.           Example: 4n   correctly means 4 times n                           n4   incorrect Another acceptable method of writing multiplication is to use parentheses.           Example: 4(n) – correctly means 4 times n – notice there is no symbol between the number and the parentheses To write division using variables we rarely use the ¸ symbol, we usually use the fraction bar.             Example: 8¸n or   is correctly written An expression is a group of symbols that does not contain an equal sign. Because it has no equal sign, it cannot be solved.           Example: 4 + b We cannot solve the expression listed above because we do not know what b represents. An equation is an expression or group of expressions that has an equal sign. An equation can be solved.          Example: 4 + b = 10 We can solve this because we know that b must equal 6.