The radio station gave away a discount coupon for every twelfth and thirteenth caller. Every twentieth caller received free concert tickets. Which caller was the first to get both a coupon and a concert ticket? Explain your thinking.

“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 .