Note for the first part of the question we are being asked h

Note: for the first part of the question we are being asked how much in terms of ratio meaning there has to be a calculation. Thank you for your help

For sun,

B - R= -2.5 log (FB/FR)=0.62 (yellow color based on the color ratio diagram)

where, F is the fluxes of the star.Plug the flux formula which is in relation with temperature and waveength.

For Sirius,

B - R= -2.5 log (FB/FR)=0.00 (Color is blue).