2. Упростите выражение: 1) -1,6x × (-5y); 2) -7a - 9b + a + 11b; 3) a - (a - 8) + (12 + a); 4) -3(c - 5) + 6(c + 3).

1) -1,6x × (-5y) = 8xy 2) -7a - 9b + a + 11b = -6a + 2b 3) a - (a - 8) + (12 + a) = a - a + 8 + 12 + a = a + 20 4) -3(c - 5) + 6(c + 3) = -3c + 15 + 6c + 18 = 3c + 33