[tex]3b+(b+1) = \underline {3b}+\underline {b}+1=4b+1\\\\5a-(a+1)=\underline {5a}-\underline {a}-1=4a-1\\\\3-(4x-6y+2)+(2x-7y)=3\ \underline {-\,4x}\ \underline {\underline {+\,6y}}-2\ \underline {+\,2x}\ \underline {\underline {-\,7y}}=\\\\{}\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad =1-2x-y[/tex]
[tex](2a+1)-(3a-2)=\underline{2a}+1\, \underline{-\,3a}+2=-a+3\\\\a=-4\\\\-a+3=-(-4)+3 = 4+3=7\\\\\\(2x+y)+(x-5)-(6-2y)=\underline{2x}\,\underline{\underline{+\,y}}\,\, \underline{+\,x}-5-6\,\underline{\underline{+\,2y}}=3x+3y-11\\\\x=3\,,\ \,y=(-2)\\\\3x+3y-11=3\cdot3+3\cdot(-2)-11=9-6-11=3-11=-8[/tex]
