What's the formula for area of a triangle

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Read the excerpt from gilgamesh: a new english version. gilgamesh backed away. he said,"how dreadful humbaba's face has become! it is changing into a thousand nightmarefaces, more horrible than i can bear. i feel haunted. i am too afraid to go on." §enkidu answered, "why, dear friend, do you speak like a coward? what you just saidis unworthy of you. it grieves my heartwe must not hesitate or retreat."

Ahyperbola centered at the origin has a vertex at (-6,0) and a focus at (10,0). what are the directrices?