Explanation:
To find : Write a variable expression the algebraic expression ?
Solution :
A variable is defined as the symbol for a number we don't know yet.
It is usually a letter like x or y.
1)
The variable in the expression is unknown value i.e. x.
2)
The variable in the expression is unknown value i.e. x.
3)
The variable in the expression is unknown value i.e. x.
4)
The variable in the expression is unknown value i.e. 'a' and 'b'.