Answer:
substitute the values given,
= (2a + b) - (a - 2b)
= (2(x + 2y) + x - 2y) - (x + 2y - 2(x - 2y))
= (2x+4y+x-2y) - (x+2y-2x+4y)
= (3x+2y) - (-x+6y)
= 3x + 2y + x - 6y
= 4x - 4y
then,
(2a+b) - (a-2b) = 4x - 4y
