{5又9分之5-0.8+2又9分之4}*{7.6/5分之4+2又5分之2*1.25}
={5又9分之5+2又9分之4-0.8}*{7.6*1.25+2.4*1.25}
=7.2*(7.6+2.4)*1.25
=8*1.25*0.9*10
=90