[tex]39. \ 3x^{2}-5y+x^{2}+5y+7 = 3x^{2}+x^{2}-5y+5y+7 = \boxed{4x^{2}+7}\\\\Odp. \ D.[/tex]
[tex]40. \ (5x-6)-(3+x) =5x-6-3-x = 5x-x -9 = \boxed{4x-9}\\\\Odp. \ A.[/tex]
[tex]41. \ a-3b+3(a-b) =a-3b+3a-3b = a+3a -6b= \boxed{4a-6b}\\\\Odp. \ A.[/tex]
[tex]42. \ 3,5a^{3}b\cdot(-1,2)\cdot ab^{2}=3,5\cdot(-1,2)\cdot a^{3}\cdot a \cdot b\cdot b^{2}=\boxed{-4,2a^{4}b^{3}}[/tex]
