Solve the Algebraic Expression: 12z + 3m - (m-z)

We begin by addressing the parenthesis:

Remember that:

When we multiply a positive number by a negative number, the result will be negative.

When we multiply a negative number by a negative number, the result will be positive.

Hence we obtain the following calculation:

$12z+3m-m+z=$

Next we join together the z coefficients:

$12z+z=13z$

We then join together the m coefficients:

$3m-m=2m$

Finally we obtain the following:

$13z+2m$