Circle the problems below that you could use mental math to solve.

Hello!

For this one, all of them look like you can use mental math, but maybe choose the two middle ones and the bottom right one. 

Hope this helps :))

Maybe 54-10 because you just take one away from 5

“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 .

11 mintues is the naswer