Use the associative property to identify which expression is equal to (21)(7)(3x).

 hello : 
 (21)(7)(3x) = (21×7×3)(x) = 441x 

“exterior angles of triangles. an exterior (or external) angle is the angle between one side of a triangle and the extension of an adjacent side. try this drag the orange dots on any vertex to reshape the triangle.” look to get to the answer i explained what it means and other things i hope it you .