Tolong bantuin jawab ya

2. a. 7x – 15y -5x – 9y
7x – 5 x – 15y – 9y
2x – 24y

b. 5y -3x -4 -5x – 3y + 7
5y -3y -3x – 5x -4 + 7
2y – 8x + 3

c. 5x^2 -9xy -4y^2 + x^2 + 6xy +3y^2
5x ^2 + x^2 – 9xy + 6xy – 4y^2 +3y^2
6x ^2 – 3xy -y^2

^ = pangkat