[tex]\displaystyle\bf\\\begin{cases}\displaystyle\bf a+b=154\\\\\displaystyle\bf\frac{a}{3}+b-4=66~~\Big|\times3\\\end{cases}\\\\\\\begin{cases}\displaystyle\bf a+b=154\\\displaystyle\bf a+3b-12=198\\\end{cases}\\\\\\\begin{cases}\displaystyle\bf a+b=154\\\displaystyle\bf a+3b=198+12\\\end{cases}\\\\\\\begin{cases}\displaystyle\bf a+b=154~~~\Big|\times(-1)\\\displaystyle\bf a+3b=210\\\end{cases}\\\\\\[/tex]
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[tex]\displaystyle\bf\\\begin{cases}\displaystyle\bf -a-b=-154\\\displaystyle\bf a+3b=210\end{case}\\\\- - - - - - - -\\~~~~~/+2b=56\\\\b=\frac{56}{2}\\\\\boxed{\bf b=28}\\\\a+b=154\\\\a+28=154\\\\a=154-28\\\\\boxed{\bf a=126}[/tex]
