Answer
$5m+7n-15$
Work Step by Step
$\bf{\text{Solution Outline:}}$
Use the Distributive Property to simplify the given expression, $
2m+n-3(5-m-2n)
.$ Then combine like terms.
$\bf{\text{Solution Details:}}$
Using the Distributive Property which is given by $a(b+c)=ab+ac,$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
2m+n-3(5-m-2n)
\\\\=
2m+n-3(5)-3(-m)-3(-2n)
\\\\=
2m+n-15+3m+6n
.\end{array}
By combining like terms, the expression above is equivalent to
\begin{array}{l}\require{cancel}
2m+n-15+3m+6n
\\\\=
(2m+3m)+(n+6n)-15
\\\\=
5m+7n-15
.\end{array}
