Add :
`7xy , 2xy , - 8xy`

Add : 7xy , 11xy

Add: 7xy + 5yz - 3zx, 4yz + 9zx - 4y, - 3xz + 5x - 2xy

Simplify : 7xy - 3xy - 6xy + xy - 5xy

Simplify the following : 7xy - 4xy - 3xy - 11 xy + 5xy - xy

Add : 13ab - 9cd - xy, 5xy, 15cd - 7ab, 6xy - 3cd

Simplify the following : 3xy^(2) - 5x^(2)y + 7xy - 9xy^(2) - 4xy + 6x^(2)y

Multiply : 3x^(2) y - 7xy^(2) +2xy" by " 4xy

Add : x^(3) - x^(2)y + 5xy^(2) + y^(3) , -x^(3) - 9xy^(2) + y^(3), 3x^(2)y + 9xy^(2)

Solve: 3 (2x+ y ) = 7xy 3(x+ 3y ) = 11xy , x ne 0 , y ne 0

Find the sum of the following algebraic expressions : 4xy - 3yz + 2zx , 2xy - yz - zx , - xy + 5yz + 6zx