a: \(79\cdot25+75\cdot79\)
\(=79\cdot\left(25+75\right)=79\cdot100=7900\)
b: \(\left(323-576\right)-\left(224-476\right)\)
\(=323-576-224+476\)
=99-100=-1
c: \(\dfrac{4}{5}-1,2+3\dfrac{1}{2}-25\%\)
\(=0,8-1,2+3,5-0,25\)
=3,1-0,25
=2,85
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