7=6-4, +4r
Please help

Simplify (4x^2 - 8xy + 2y^2) - (9x^2 - 4xy - 7y^2) a. -5x^2 + 4xy + 9y^2 b. -5x^2 - 4xy + 9y^2 c. -5x^2 + 12xy + 4y^2 d. -5x^2 - 4xy - 5y^2

(60 points) explain this in detail

y=2x−1 5x−4y=1 is (1,1)(1,1) a solution of the system?