I need help w this pls

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Write an inequality for this description. - one fourth of the opposite of the difference of five and a number is less than twenty.

Describe the end behavior of the function below. f(x)=(2/3)^x-2 a. as x increases, f(x) approaches infinity. b. as x decreases, f(x) approaches 2. c. as x increases, f(x) approaches -2. d. as x decreases, f(x) approaches negative infinity.