Ответ:

  1. \(165.64-(a-12.5)=160.54\)

    \(a-12.5=165.64-160.54=5.1\)

    \(a=5.1+12.5=17.6\)

  2. \(278.74-(6.5-b)=276.84\)

    \(6.5-b=278.74-276.84=1.9\)

    \(-b=1.9-6.5=-4.6\)

    \(b=4.6\)

Ответ: \(a=17.6\); \(b=4.6\).