[tex]\left\{\begin{aligned}&[\left(3+a\div 2\right)\div 11+7]\times 5-8 = 42\\&[\left(3+a\div 2\right)\div 11+7]\times 5= 42+8 \\ &[\left(3+a\div 2\right)\div 11+7]\times 5= 50\end{aligned}\right.[/tex]
[tex]\left\{\begin{aligned}&(3+a\div 2)\div 11+7= 50\div 5\\&(3+a\div 2)\div 11+7= 10\end{aligned}\right.[/tex]
[tex]\left\{\begin{aligned}&(3+a\div 2)\div 11= 10-7\\&(3+a\div 2)\div 11= 3 \end{aligned}\right.[/tex]
[tex]\left\{\begin{aligned}&3+a\div 2= 3\times 11 \\&3+a\div 2= 33 \end{aligned}\right.[/tex]
[tex]\left\{\begin{aligned}&3+a\div 2= 33-3 \\&a\div 2= 30 \end{aligned}\right.[/tex]
[tex]\left\{\begin{aligned}&a= 30\times 2\\ &a = 60 \end{aligned}\right.[/tex]
Răspuns:
a = 60
