What two numbers add to 12 and multiply to -160

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76

The boiling point of water at an elevation of 0 feet is 212 degrees fahrenheit (°f). for every 1,000 feet of increase in elevation, the boiling point of water decreases by about 2°f. which of the following represents this relationship if b is the boiling point of water at an elevation of e thousand feet? a) e = 2b - 212 b) b = 2e - 212 c) e = -2b + 212 d) b = -2e + 212

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.