How to determine the missing side length

There were 816 people at a concert when a band started to play. after each song, only half the people stayed to hear the next song. how many people were left at the concert after x songs? write a function to represent this scenario.

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

Aplot of land is shaped like a quadrilateral. fences are built on the diagonal to divide the area into 4 sections. what is vi to the nearest tenth? gv = 6.55fv = 5.84vh = 3.27vi = ?