1: \(=176+324+228+272=500+500=1000\)
2: \(=526-326-131+321=200+190=390\)
3: \(=545\left(65+15\right)-80\cdot445\)
\(=80\left(545-445\right)=80\cdot100=8000\)
\(1,=\left(176+324\right)+\left(228+272\right)=500+500=1000\\ 2,=\left(526-326\right)+\left(321-131\right)=200+190=390\\ 3,=545\left(65+15\right)-80.445=545.80-80.445=80\left(545-445\right)=80.100=8000\\ 4,=31\left(175-50\right)+69.125=31.125+69.125=125\left(31+69\right)=125.100=12500\\ 5,=43\left(78-48\right)+30\left(80-23\right)=43.30+30.57=30.\left(43+57\right)=30.100=3000\\ 6,=64\left(57+43\right)-2300=64.100-2300=6400-2300=4100\)
4) 31. (175-50)+69.125
=31.125+69.125
=125. (31+69)
=12500
5)43.78-43.48+30.80-30.23
=43. (78-48)+30. (80-23)
=43.30+30.57
=30 . (43+27)
=30.100
=3000
6)64+57.64+43-2300
=64. (57+43)-2300
=64.100-2300
=6400-2300
=4100
