Let's expand the left side of the equation:

3*(1.4x - 3.5) = 4.2x - 10.5

Now we can rewrite the equation with the expanded left side:

4.2x - 10.5 = -2.3x - 9

Next, let's simplify the equation by combining like terms:

4.2x + 2.3x = 10.5 - 9
6.5x = 1.5

Finally, we solve for x by dividing both sides by 6.5:

x = 1.5 / 6.5
x = 0.230769

Therefore, the solution to the equation is x = 0.230769.