We can add and structure only like quantities.\\\\(\\Rightarrow\\\\) Dimensions of \\\\(P\\\\) = Dimensions of \\\\(\\dfrac{a}{V^2}\\\\) ...... (i) and dimension of \\\\(V\\\\) = Dimensions of b ............ (ii)From (i), Dimensions of a = Dimensions of \\\\(P \ imes\\\\) Dimensions of \\\\(V^2 [a]\\\\) \\\\( = [M^1L^{-1}T^{-2}] \ imes [L^3]^2\\\\) \\\\( = [M^1 L^5 T^{-2}]\\\\)Unit of \\\\(a =\\\\) Unit of \\\\(p \ imes Unit \\,\\,of \\,\\, v^2 \\\\) \\\\(= \\dfrac{N}{m^2} \ imes m^6 = N m^4\\\\)From (ii), [b] = \\\\([V] = [M^0L^3T^0]\\\\)So unit of b = Unit of V = \\\\(m^3\\\\)