To solve the equation (2+x)×3.1=-12.4:

First, distribute the 3.1 to (2+x):

6.2 + 3.1x = -12.4

Subtract 6.2 from both sides:

3.1x = -18.6

Divide by 3.1:

x = -6

Therefore, the solution to the equation (2+x)×3.1=-12,4 is x = -6.

To solve the equation (-1.9)×(-2.4)=12:

Multiply -1.9 by -2.4:

-1.9 * -2.4 = 4.56

Therefore, the solution to the equation (-1,9)×(-2,4)=12 is 4.56.