${C_1} = C,{C_2} = \frac{C}{2}\,\,{T_1}\, = \,600K\,\,{T_2}\, = \,\,700\,K\,\,\pi = CRT$
$\therefore \frac{{{\pi _1}}}{{{\pi _2}}} = \frac{{{C_1}R{T_1}}}{{{C_2}R{T_2}}}$
$\therefore \frac{P}{2} = \frac{{2 \times C \times R \times 60}}{{C \times R \times 700}}$
$\therefore P = \frac{{24}}{7}$