Use the supplied three-factor planning model W=3D−F−R−H, where W is water temperature, D target dough temperature, F flour temperature, R room temperature and H an empirical friction factor, all in °C. D=26, F=22, R=26, H=6. This is an algebra exercise, not a universal physical mixing law. Hold unmentioned factors constant.
Calculate the required water temperature under the model in °C. Keep intermediate values unrounded; round the final answer to 4 decimal places if needed.