2/3 of the way from 6 to 12 would be 10. Agreed?
2/3(12-6) = 2/3 (6) = 4 6+4=10 That is how to find it more formally.
so
Given R(-6,19) and S(15,-5), what are the coordinates of the point on segment RS two-thirds of the distance from R to S?
the x value will be -6 + 2/3(15 - -6)
and you can find the y value