Four times the sum of 16 and a number

On a piece of paper graph f(x)=5•(0.4)^x

What is the value of n in the equation -1/2(2n+4)+6=-9+4(2n+1)

Will give brainliest b. describe the function over each part of its domain. state whether it is constant, increasing, or decreasing, and state the slope over each part.