$6m^8-18m^6-6m^4$  

 $54m^8-18m^2-6m^5$  

 $54m^{8\ }-18m^6-6m^5$  

Is an expression containing two or more algebraic terms

is an expression containing one algebraic terms

$x^{m+n}$

$\frac{x^m}{x^n}=x^{m-n}$

Describing and predicting traffic patterns

Solve geometry problems involving perimeter