Question 121890
pV=240 __ V=240/p


pV=(p-1)(V+20) __ pV=pV+20p-V-20 __ 0=20p-V-20


substituting for V __ 0=20p-(240/p)-20


multiplying by p __ 0=20p^2-20p-240 __ dividing by 20 __ 0=p^2-p-12


factoring __ 0=(p-4)(p+3)