a) −27+27:357−2​+72​:53​

b) −819+−421−1721+271919−8​+21−4​−2117​+1927​

c) 65.313−65.161356​.133​−56​.1316​

a) −27+27:357−2​+72​:53​

=−27+27.53=7−2​+72​.35​

=−27+1021=7−2​+2110​

=−621+1021=21−6​+2110​

=421=214​

b)−819+−421−1721+271919−8​+21−4​−2117​+1927​

=−819+−421+−1721+2719=19−8​+21−4​+21−17​+1927​

=(−819+2719)+(−421+−1721 )=(19−8​+1927​)+(21−4​+21−17​ )

=−8+2719+(−4)+(−17)21=19−8+27​+21(−4)+(−17)​

=1919+−2121=1919​+21−21​

=1−1=0=1−1=0

c) 65.313−65.161356​.133​−56​.1316​

=65.(313−1613 )=56​.(133​−1316​ )

=65.(3−1613)=56​.(133−16​)

=65.(−1313)=56​.(13−13​)

=65.(−1)=56​.(−1)

=−65.=5−6​.

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