A bird is flying at an altitude of 100 feet. After a few minutes of ascending and descending, the bird ends up at a new altitude of 120 feet. Which of the following expressions best represents the flight of the bird?
A: 100 + 30- (- 50)

B: 100 + (-30) + (- 50)

C: 100 + 30+ 50

D: 100 + (-30) + 50

Four individuals pool money together to start a new business and agree to split the profits equally. n invests $6,000, x invests $2,000, y invests $8,000 and z invests $4,000. if the profits for the first month were $100,000, y receives than if the profits were divided in proportion to how much they invested.