(3-х)(2+х)+(5-х)(6-х) =

= (6+3х-2х-х^2)+(30-5х-6х+х^2) =

= (6+х-х^2)+(30-11х+х^2) =

= 6+х-х^2+30-11х+х^2 =

= 36-10х = 2(18-5х) = 2(18-5*3/20) =

= 69/2 = 34,5

Ответ : 34,5