Quick introduction to Algebra 1

Variables are symbols that represent varying values, and that’s why we call it variables. Variables are used anywhere you could need a placeholder to represent an unknown value.

For Example, I work in a restaurant and I am making 12$ an hour, on top of that i also get some tips each hour,

So the below expression shows, how much I might make in a given hour,

$12 + tips

The value of tips can change dramatically each hour, in lunch time, people may give big amounts, and the next hour, I may not have any customers, and so, I may get nothing.

So the ‘tips’ part of the above expression change from scenario to scenario, and thus called a variable.

Think of Algebra as a puzzle, where we have an equation and the equation need to be balanced on both sides.

Eg 1 : What is the missing number?

X-3=9

In this case X just means “we don't know the value of this", and so it is called the unknown or the variable. In Algebra we use letters say x, y or w or any letter of the alphabet.

How to solve it?

Work out what to remove to get "x = ..."

Remove it by doing the opposite (adding is the opposite of subtracting)

Do that to both sides.

Here is an example:

Eg 2:

Solve X+7=11

Eg 3: Solve 2+x=11

2+x-2=11-2 

x+0=9 

x=9 

Eg 4:  Solve x-5=13

x-5+5=13+5 

x+0=18 

x=18 

Eg 5: Solve 10+x=12

10+x-10=12-10 

x+0=2 

x=2