Answer
This statement is false.
The true statement would be:
If $3x + 7 = 0$, then $x = -\frac{7}{3}$.
Work Step by Step
This statement is false.
If we solve this equation for $x$, we first subtract $7$ from both sides:
$3x = -7$
We then divide each side by $3$:
$x = -\frac{7}{3}$
The statement is false because the value for $x$ should be negative.
The statement would be true if it read:
If $3x + 7 = 0$, then $x = -\frac{7}{3}$.
