Count : To count means to find out the number of objects by adding one for every object.

Length : Length is the attribute of a one-dimensional shape that can be measured with a measuring tape.

Number : A number $x$ is a mathematical symbol representing a quantity.

Number : A number $x$ is a mathematical symbol representing a quantity.

Addition : Addition is the mathematical operation that describes increasing a number by an amount equal to a second number. The mathematical symbol for addition is the plus sign $+.$ The term addition is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Equation : An equation is a mathematical statement in which two expressions are written with an equal sign in between. A solution of an equation is a set of variables that makes the statement a true statement.

Equivalence : Equivalent fractions are fractions that represent the same number. Equivalent equations or inequalities are equations or inequalities that have the same set of solutions.

Inequality : An inequality is a statement that contains an inequality sign between two expressions.

Inequality sign : The word inequality sign refers to any of $\lt,$ $\gt,$ $\leq$ and $\geq.$

Multiplication : Multiplication is the mathematical operation that is a shorthand for adding the same amount several times. For example $3\cdot 4=4+4+4=12.$

Number : A number $x$ is a mathematical symbol representing a quantity.

Positive : Positive means $\geq 0.$

Subtraction : Subtraction is the mathematical operation that describes decreasing a number by an amount equal to a second number. The mathematical symbol for subtraction is the minus sign $-.$ The term subtraction is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Term : If an expression can be written as a sum of several parts we call these parts terms.