Answer: The number of rolls of paper is \(2\dfrac{1}{2}\).
Step-by-step explanation: Given that Andy is hanging wallpaper in his kitchen. 6 rolls of wallpaper is used to cover \(2\dfrac{2}{5}\) of the walls.
We are to find the number of rolls of paper used per wall.
We will be using unitary method to solve the given problem.
We have,
\(2\dfrac{2}{5}=\dfrac{12}{5}.\)
Now, number of rolls used to cover \(\dfrac{12}{5}\) of the walls = 6.
Therefore, number of rolls used to cover 1 wall is given by
\(\dfrac{6}{\frac{12}{5}}=\dfrac{5\times 6}{12}=\dfrac{5}{2}=2\dfrac{1}{2}.\)
Thus, \(2\dfrac{1}{2}\) rolls of paper used per wall.