To determine the volume of oil that was displaced, we do summation of forces around the block of wood. Two forces are involved namely the weight and the buoyant force which are in opposite directions. We do as follows:
W - Fb = 0
W = Fb
m(wood)g = m(oil)g
m(wood) = m(oil displaced)
m(wood) = density (V(oil displaced))
1500 g = 0.7500 g / cm^3 (V(oil displaced))
V(oil displaced) = 2000 cm^3