I think I see what you are saying. They are simply asking for the slope though, not the absolute value of the slope.
So we know the Y int for N is greater than Y int of P. Let's look at the different situations.
N>1
P>1
therefore the slope for line N is negative and the slope for line P is negative, but it still has to be less of a negative slope than N. For example, N may have a -5 slope, but P will have a -3.
N>1
P<1
Here the slope for line N is negative, and the slope of line P is positive. So Slope N<Slope P
N<1
P<1
Both slopes will be positive, but line P will have a greater slope, because it will be a steeper line since the Y int of P< the Y int of N
In all 3 situations the slope of P is greater than the slope of N.
I hope that made sense.