# Using Symbols

Symbols are very commonly used in equations. They are used to represent unknown numbers.

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## Other Math Activities:

Fun with Equations

Observe the following sentences:

1) +  8 = 10

2)  (___x 4) x 2 = 24

3)  5 - ( ) =3

,( ) are the symbols used for unknowns.

In Algebra, x, y, z, a, b, c, l, k.., are common symbols used for unknowns and are called variables. Above examples in Algebra can be written as:

1)   X + 8 = 10

2)   (a x 4) x 2 = 24

3)   5 - h = 3

Equation: A mathematical open sentence containing the sign 'equal to' is called an equation.

Examples:

1)  3 + X =5

2)  14 = 19 - Y

3)  15 x Q = 45

Word Problem:

Rosa has 12 marbles. Four of them are blue, and the rest are green. How many green marbles does Rosa have?

First, create a math sentence for this problem:

Four blue marbles + some green marbles = 12 marbles

Let there be ' X ' number of green marbles;

Therefore, the math sentence becomes:

4 blue marbles + ' X ' green marbles = 12 marbles

4 + X = 12

X = 12 - 4

X = 8