The coordinates of point P would be (2.6, 1.6).
The ratio of the sides being 3:7 means that the segment JP would be 3/10 of the total and PK would be 7/10 of the segment.
The slope of JK is given by finding the rise/run; in this case that is 4/2=2. Since JP is 3/10 of the segment, we add 3/10 of the rise to the x-coordinate and 3/10 of the run to the y-coordinate:
(3/10(2)+2, 3/10(2)+1)
=(6/10+2, 6/10+1)
=(2.6, 1.6)