Question

15a+{a-2[3a+3b-4(5a+6b)]}

Answer 1

$15a + (a - 2(3a + 3b - 4(5a + 6b)) \\ 15a +(a - 2(3a + 3b - (20a + 24b) \\ 15a + (a - 2(3a + 3b - 20a - 24b) \\ 15a + (a - 2( - 17a - 21b) )\\ 15a + (a - ( - 34a - 42b) \\ 15a + (a + 34a + 42b) \\ 15a + (35a + 42b) \\ 50a + 42b$