A researcher is trying to maximize a Chemical Deposition Rate. A full factorial experiment is run on 2 factors, Chemical Flow Rate and RD Power. Flow Rate (X1) is run at 17 and 21 SCCM. RF Power (X2) is run at 160 and 200 W. There are also center points run at Flow Rate=19 SCCM and RF Power = 180 W. The results show that there are no quadratic (curvature) effects and no interaction. The main effects are both significant. The regression equation is: Y= 15.4 + 0.85 X1 + 0.50 X2 The next step is to run a Slope of Steepest Ascent. The first run of the Flow Rate will be at 21 SCCM. What will be the corresponding first run for the RF Power