（0.75×5734-0.574×25+57.4）÷3
=（0.75×5734-0.25×57.4+57.4）÷3
=【0.75×5734+57.4×（1-0.25）】÷3
=（0.75×5734+57.4×0.75）÷3
=0.75×（5734+57.4）÷3
=0.25×5791.4
=1447.85