2(4x + 3y) (x - y) - (x + y) (3x + 4y)
Expanding the expression, we have:
2(4x + 3y)(x - y) - (x + y)(3x + 4y)
= (2)(4x)(x) + (2)(4x)(-y) + (2)(3y)(x) + (2)(3y)(-y) - (x)(3x) - (x)(4y) - (y)(3x) - (y)(4y)
= 8x^2 - 8xy + 6xy - 6y^2 - 3x^2 - 4xy - 3xy - 4y^2
= 5x^2 - 16xy - 10y^2