Reduce as much as possible. 12/32

In triangle abc segment de is parallel to the side ac . (the endpoints of segment de lie on the sides ab and bc respectively). find de, if ac=20cm, ab=17cm, and bd=11.9cm;

In a school 2/3 of the students study a language of those who study a language 2/5 study french

The interior angles formed by the sides of a hexagon have measures that sum to 720°. what is the measure of angle a? enter your answer in the box. m∠a= °