Sagot :
(4a^2 - 5a + 6) - (2a^2 + 3) - (9 - 6a)
combine like terms
4a^2 - 2a^2 - 5a + 6a + 6 -3 -9
2a^2 + a - 6 <- Answer
combine like terms
4a^2 - 2a^2 - 5a + 6a + 6 -3 -9
2a^2 + a - 6 <- Answer