An equation is a mathematical statement that two values are equal.
Sometimes part of an equation is unknown.
Unknown values can be represented by a variety of letters and/or symbols.
To find the unknown number, the equation can be thought of as:
2 times 5 equals some number.
Since 2 times 5 equals 10, the unknown number is 10.
To find the unknown number, the equation can be thought of as:
some number times 5 equals 20.
Since 4 times 5 equals 20, the unknown number is 4.
Or, using the relationship between multiplication and division, the solution can be found by dividing 20 by 5.