39.9*2.75+27.5*611-2.75

717.975

39.9*2.75+27.5*611-2.75
=39.9×2.75+2.75×61.1-2.75
=2.75×（39.9+61.1-1）
=2.75×100
=275

你好:
原式=39.9*2.75+27.5*611-2.75
=2.75 * (39.9 + 10 * 6.11 - 1)
=2.75 * (39.9 + 61.1 -1)
= 2.75 * (100 - 1)
= 2.75 * 100 - 2.75 * 1
=275 - 2.75
=272.25