Can someone please help me with math.

Solve: 3x+y=6 4x-2y=18 show all work !

Two variables, x and y, vary inversely, and x=12 when y=4. what is the value of y when x=3?

Someone answer asap for ! 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