We can make a system of equations:
Joseph: 4n+3p=11
Patrick: 3n+5p=11
Luckily enough, they are both equal to 11, so this is easy to solve. Just put the two together like this and solve for n:
4n+3p=3n+5p
n+3p=5p
n=2p
Plug 2p into either equation for n:
4(2p)+3p=11
8p+3p=11
11p=11
p=1
So a pen is $1, and that must mean a notebook must be $2 because it costs twice as much as a pen.
Hope this helped! Feel free to message me with any more questions.
