2x+5y=20 y=-0.4x-1 i really need help over here

Complete the standard form of the equation that represents the quadratic relationship displayed above, where a, b, and c are rational numbers.

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

If you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left