Dalton's law: partial pressure of a gas = mole fraction × total pressure of the mixture. $p_1 = x_1p$, $p_2 = x_2p$, $p_3 = x_3p$ and $p = p_1 + p_2 + p_3$ (also $p = n_1\frac{RT}{V} + n_2\frac{RT}{V} + n_3\frac{RT}{V}$) $p_i = x_ip_i^\circ$ (with $p_i^\circ$ = pressure of the pure component) is the form of Raoult's law, not Dalton's law – so it is not correct.