- Variables: the word variable means something that can vary. A variable takes on different numerical values, its value is not fixed. It is denoted by letters of alphabets such as a, x, y, z, l, m etc.
- Equation: an equation is a condition on a variable. The condition is that two expressions should have equal value and at least on of the two must contain the variable.
- Equality sign: the equality sign shows that the value of the expression to the left of the sign is equal to the value of the expression to the right of the sign.
- Transposing: transposing means moving to the other side.