I am not understanding about the market interest rate , that last sentence ,about more of it the lower the market interest rate is?

RM R-M RM s (16.6) .+ +...+ + 1+: (1+::)2 0+5)\" 0+5)\" PV: The cost of the machine is simply its purchase price, PK. The rm should buy the machine if and only if PV is greater than or equal to PK. We see from Equation 16.6 that PV is inversely related to the market rate of interest. Thus, as with the rm that rents its equipment, the rm that owns its capital will want to employ more of it the lower the market rate of interest is