How to solve x^2-4x-5=0 by using the quadratic formula?

Find the solution of system of equation y= x-4 y=4x+2

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

The difference of two numbers is 40. find the numbers if 0.3 parts of one number is equal to 37.5% of the other one.