1. Start with the equation: 
    3(5 - 2x) = 7x + 6  
2. Distribute the 3 on the left side:
    15 - 6x = 7x + 6  
3. Rearrange the equation to bring all terms involving \(x\) to one side:
    -6x - 7x = 6 - 15  
4. Combine like terms:
    -13x = -9  
5. Solve for \(x\) by dividing both sides by \(-13\):
    x = \frac{-9}{-13}  
6. Simplify the expression:
    x = \frac{9}{13}  
Thus, the unique rational solution is \( x = \frac{9}{13} \).