The distributions of incomes in the two cities follow two Pareto type pdfs

f(x) = 2/x^3 1 < x < infinity and g(y) = 3/y^4 1 <y < infinity

Here one unit represents 20,000 dollars. One person with income is selected at random from city and let X and Y be their respective incomes.

Compute P(X < Y)

how do you compute that probability. I'm not sure how to approach P(X<Y).