Ответ:

а)

\(623 - 518.2 = 104.8\);

\(0.55 \cdot 104.8 = 57.64\);

\(1.24 \cdot 68 = 84.32\).

\(57.64 + 84.32 - 1.96 = 140\).

Ответ: 140.

б)

\(88.74 - 18.54 = 70.2\);

\(70.2 \cdot 0.009 = 0.6318\);

\(0.6318 - 0.6218 = 0.01\);

\(0.01 \cdot 400 = 4\).

Ответ: 4.