a) (1989.1990+3978):(1992.1991-3984)
=\([\)1989.1990+1989.2\(]\):\([\)1992(1989+2)−3984\(]\)
= \([\)1989(1990+2)\(]\):\([\)1992.1989+1992.2−3984\(]\)
=(1989.1992):(1992.1989+3984−3984)
=(1989.1992):(1992.1989)
\(\Rightarrow\)=1
b) (637.527-189)/(526.637+448)
=(637.526+637-189)/(526.637+448)
=(637.526+448)/(637.526+448)
\(\Rightarrow\)=1