原式=59/6 x17/4+17/4x1/6=17/4x(59/6+1/6)=85/2
9又5/6*4.25+4又1/4除以6=9又5/6×4.25+4又1/4×1/6=4.25×（9又5/6 + 1/6）=4.25×10=42.5
