we have that
A (-8, -2) and B(16,6)
step 1
find the distance AB in the x coordinates
dABx=(16-(-8))-----> 24 units
step 2
find coordinate x of P (Px)
Px=Ax+(3/5)*dABx------> Px=(-8)+(3/5)*24----> 6.4
step 3
Find the distance AB in the y coordinates
dABy=(6-(-2))-----> 8 units
step 4
find coordinate y of P (Py)
Py=Ay+(3/5)*dABy------> Py=(-2)+(3/5)*8----> 2.8
the coordinates of P are (6.4,2.8)
see the attached figure