Let's first simplify the equation step by step:

-(3+2x-10.5) + 2.4 = 3.1(4-x)

Now simplify the terms inside the parentheses:

Next, distribute the negative sign inside the parentheses:

-2x + 7.5 + 2.4 = 3.1(4 - x)

Combine the constants:

5.9 - 2x = 3.1(4 - x)

Now distribute on the right side:

5.9 - 2x = 12.4 - 3.1x

Now we want to isolate the x variable:

Add 3.1x to both sides:

5.9 - 2x + 3.1x = 12.4

Combine x terms:

5.9 + 1.1x = 12.4

Subtract 5.9 from both sides:

1.1x = 6.5

Now, divide by 1.1 to solve for x:

x = 6.5 / 1.1

x = 5.9091

Therefore, the solution to the equation is x = 5.9091.