=+39. The accompanying data on x 5 frequency (MHz)

and y 5 power (W) for a certain laser configuration was read from a graph in the article “Frequency Dependence in RF Discharge Excited Waveguide CO2 Lasers” (IEEE J. of Quantum Electronics, 1984: 509–514):

x: 60 63 77 100 125 157 186 222 y: 16 17 19 21 22 20 15 5