Why can the value of the variable a in the expression a + 2 be any number? Why does the variable b in the equation b + 2 = 5 have only one value?

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(a) Because the expression is not an equation

(b) Because the expression is an equation

Step-by-step explanation:

Solving (a): a + 2

The above expression can assume any value for a because it is not an equation.

Take for instance:

a = 2;

The reason for this is because the expression is not an equation

Solving (b):

The above expression can assume only value for b, and the value is:

This means that only will make the equation true.

The reason for this is because the expression is an equation