I think I may be confusing myself. The quantity theory of money assumes that the velocity of money is constant. If velocity is constant, its growth rate is zero and the growth rate in the money supply will equal the inflation rate (the growth rate of the GDP deflator) plus the growth rate in real GDP. This also means that the inflation rate is equal to the growth rate of the money supply minus the growth rate of output. If the money supply grows faster than output, the economy will experience inflation. If the money supply grows at the same rate as output, the price level will be stable. So using the equation of exchange, what would be the impact of an increase in the money supply if velocity and output are stable?