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

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.

Multiple : A multiple of a number $x$ is any of the numbers $1x,2x,3x,4x,\ldots.$ For example the multiples of 7 include 7, 14, 21 and 70.

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.

Negative : A number is negative if it is $\lt 0.$

Solution : A solution to an equation is a choice of variables that when substituted into the equation results in a true statement.