Algebra: A Combined Approach (4th Edition)

a = $-\frac{3}{2}$
4(3 - a) - (6a + 9) = -12a Distribute: 12 - 4a - 6a - 9 = -12a Combine like terms: -10a + 3 = -12a Add 12a to both sides: 2a + 3 = 0 Subtract 3 from both sides: 2a = -3 Divide both sides by 2: a = $-\frac{3}{2}$