tolong bantu plissss!!!!!!!!!

1. 2x (karung beras) + 5y(kg)
2. 4x + 3y + 6z - 2x - 1x - 2x
4. 5x - 9y + 2z + 16x -12y + 4
= 5x - 16x -9y + (-12y) +2z +4
= -11x -21y + 2z +4
5. 4a + 3b - 6a -2b
= 4a + (-6a) - 3b - 2b
= -2a -5b