Let's first distribute and simplify each side of the equation:

0.3(6) - 0.3(3y) = 4.5 - 0.8(y) + 0.8(9)

1.8 - 0.9y = 4.5 - 0.8y + 7.2

Next, combine like terms on each side:

1.8 - 0.9y = 11.7 - 0.8y

Now, let's isolate y on one side of the equation:

-0.9y + 0.8y = 11.7 - 1.8

-0.1y = 9.9

Finally, divide by -0.1 to solve for y:

y = 9.9 / -0.1

y = -99

Therefore, the solution to the equation is y = -99.