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A variable is a letter or a literal used to signify an unknown quantity.

Let letter b represent the age of Brenda then it is given that Max is 4 years younger thus the age of max will be $b−4$

It is given that the sum of ages of Brenda and max is 16 thus, we have:

$b+\left(b−4\right)=16$

We obtained the equation $b+\left(b−4\right)=16$, to simplify it, we open the brackets as shown:

$\begin{array}{l}b+\left(b−4\right)=16\\ b+b−4=16\end{array}$

Like terms are the terms having the same variables and are raised to the same index. A coefficient is the appended number in front of the variable; if no number is shown then we assume it to be 1.

Unlike terms are the terms not having the same variables and or are raised to a different index.

For example, 4 and$5x$ are unlike terms.

We can add like terms by adding their coefficients, we cannot add the unlike terms.

Now we are having the expression $b+b−4=16$, combining like terms we get:

$\begin{array}{l}b+b−4=16\\ 2b−4=16\end{array}$

Now we are having the expression $2b−4=16$, adding 4 both sides we get:

$\begin{array}{l}2b−4+4=16+4\\ 2b=20\end{array}$

Dividing b both sides by 2 we get:

$\begin{array}{l}\frac{2b}{2}=\frac{20}{2}\\ b=10\end{array}$

Thus Brenda’s age is 10 years.

We know that age of Max is $b−4$, plugging$b=10$ we get:

$\begin{array}{l}b−4\\ =10−4\\ =6\end{array}$

Thus, Max’s age is 6 years.