Răspuns:
[tex](13 \sqrt{3} - 2 \times (8 \sqrt{3} - 3 \sqrt{5} )) \div 3 = \\ = (13 \sqrt{3} - 16 \sqrt{3} + 6 \sqrt{5} ) \div 3 = \\ = ( - 3 \sqrt{3} + 6 \sqrt{5} ) \div 3 = \frac{ - 3 \sqrt{3} }{3} + \frac{6 \sqrt{5} }{3} = - \sqrt{3} + 2 \sqrt{5} [/tex]