\(A+7x^2y-5xy^2-xy=x^2y+8xy^2-5xy\)
\(\Rightarrow A=\left(x^2y+8xy^2-5xy\right)-\left(7x^2y-5xy^2-xy\right)\)
\(=x^2y+8xy^2-5xy-7x^2y+5xy^2+xy\) \(=\left(x^2y-7x^2y\right)+\left(8xy^2+5xy^2\right)+\left(-5xy+xy\right)\)
\(=-6x^2y+13xy^2-4xy\)
A = (x\(^2\)y + 8xy\(^2\)- 5xy) - (7x\(^2\)y - 5xy\(^2\)- xy)
A = x\(^2\)y + 8xy\(^2\)- 5xy - 7x\(^2\)y + 5xy\(^2\)+ xy
A = (x\(^2\)y -7x\(^2\)y) + (8xy\(^2\)+ 5xy\(^2\)) + (-5xy +xy)
A = -6x\(^2\)y + 13xy\(^2\)- 4xy
A = (x\(^2\)y + 8xy\(^2\)- 5xy) - (7x\(^2\)y - 5xy\(^2\)-xy)
A = x\(^2\)y + 8xy\(^2\)- 5xy - 7x\(^2\)y + 5xy\(^2\)+xy
A= (x\(^2\)y -7x\(^2\)y) + (8xy\(^2\)+ 5xy\(^2\)) + (-5xy + xy)
A = -6x\(^2\)y + 13xy\(^2\)- 4xy