[tex]17 \times 2 + 2 \times (120 \div 12 - 2 \times (6 - a \div 6) + 6) = 50[/tex]
[tex]34 + 2 \times (10 - 2(6 - \frac{1}{6}a) + 6) = 50 [/tex]
[tex]34 + 2 \times (10 - 12 + \frac{1}{3}a + 6) = 50[/tex]
[tex]34 + 2 \times (4 + \frac{1}{3} a) = 50[/tex]
[tex]34 + 8 + \frac{2}{3}a = 50 [/tex]
[tex]42 + \frac{2}{3}a = 50 [/tex]
[tex]126 + 2a = 150[/tex]
[tex]2a = 150 - 126[/tex]
[tex]2a = 24[/tex]
[tex]a = 12[/tex]
