To solve the equation \( -\frac{x}{2.9} = -3 \), we can first eliminate the negative signs by multiplying both sides by -1:
\[ \frac{x}{2.9} = 3 \]
Next, we can multiply both sides by 2.9 to isolate \( x \):
\[ x = 3 \times 2.9 \]
Calculating that gives:
\[ x = 8.7 \]
So the solution is:
8.7