Final answer:
The value of x that makes the equation 3.1x + 3.5x = -26.4 true is -4. This is determined by combining like terms and dividing both sides by the coefficient of x.
Step-by-step explanation:
To find the value of x that makes the equation 3.1x + 3.5x = -26.4 true, you first combine like terms:
3.1x + 3.5x = 6.6x
Now, the equation becomes 6.6x = -26.4.
To solve for x, divide both sides of the equation by 6.6:
x = -26.4 / 6.6
After performing the division, you find that:
x = -4
Hence, the value of x that makes the equation true is -4.