This is simple:
\(\frac{3x}{5}\) = -6
Multiply both by 5 so the fraction cancels out
5 × \(\frac{3x}{5}\) = -6 × 5
5 and 5 cancels out
3x = -30
Divide by 3 on either sides to isolate x
\(\frac{3x}{3}\) = \(- \frac{30}{3}\)
3 and 3 cancels out
x = -10