3 + 27b + 6c is just 3 + 27b + 6c.
You can rearrange it into 3(1 + 9b + 2c), but you cannot simplify it any further.
(10x * 12 * 25y) / (2z * 30x * 20y)
= (10x / 30x) * (12 / 2z) * (25y / 20y)
= (1 / 3) * (6 / z) * (5 / 4)
= (1 * 6 * 5) / (3 * z * 4)
= 30 / (12z)
= 5 / (2z)