\(a.\) \(A=\left(15x+2y\right)-\left[\left(2x+3\right)-\left(5x+y\right)\right]\)
\(A=15x+2y-2x-3+5x+y\)
\(A=\left(15x-2x+5x\right)+\left(2y+y\right)-3\)
\(A=18x+3y-3\)
\(A=3\left(6x+y-1\right)\)
\(b.\) \(B=-\left(12x+3y\right)+\left(5x-2y\right)-\left[13x+\left(2y-5\right)\right]\)
\(B=-12x-3y+5x-2y-13x-2y+5\)
\(B=-\left(12x-5x+13x\right)-\left(3y+2y+2y\right)+5 \)
\(B=-20x-7y+5\)