Maths question

1. The problem statement, all variables and given/known data
A 2-dimensional force of 5[units] in the direction of the line y = 3x (upwards) acts through the
point P = (−1,−2). Find the moment of the force about the origin

2. Relevant equations

M = Fd

3. The attempt at a solution
i tried putting x = -1 and y = -2 into the y=3x but it doesnt work and i completely dont know how to do it.

 

i used the quation M= r X F
where OP=r = -i -2j
then i get M = (-i - 2j) X F
i dont know what to do after that to find F