spouse visa

hi all i want help i will make my sousal visa soon and i want som1 advise me plz

the income u need to sponsor a partner for a couple it's 102.75

example my wife have 3 children from her previous marriage so i want to know the income u need after rent and council tax is 282.75 ????

and i want to know if the weekly income can we add working and child tax credit and her child benifit to her weekly income bcz my wife get 250£ working and child tax credit and 170£ from her work and 185 child benifit so if we make calcul she can sponsor me with saving in her bank account
i wish i have an answer

and thnx all