a) \(=\left(278+622\right)+\left(809-209\right)=900+600=1500\)

b) \(=64.57+64.43-2300=64\left(57+43\right)-2300=54.100-2300=5400-2300=3100\)

a) 278+809+622-209
  = (278+622)+(809-209)
  =       900    +    600
  =              1500
b) 64.57+64.43-2300
  = 64(57+43)-2300
  = 64.100-2300
  = 6400-2300=4100
c) 24.5-[131-(13-4)2]
  = 24.5-(131-9.2)
  = 120-113= 7

a) \(255+312+188+645\)

\(=\left(255+645\right)+\left(312+188\right)\)

\(=900+500\)

\(=1400\)

b) \(25+12\cdot5-60\)

\(=25+60-60\)

\(=25\)

c) \(12\cdot75+12\cdot7+12\cdot18\)

\(=12\cdot\left(75+7+18\right)\)

\(=12\cdot100\)

\(=1200\)

d) \(2^4\cdot5-\left[131-\left(13-4\right)^2\right]\)

\(=16\cdot5-\left(131-9^2\right)\)

\(=80-\left(131-81\right)\)

\(=80-50\)

\(=30\)

\(2^4.5-\left[131-\left(13-4\right)^2\right]+2020^0\)

\(=16.9-\left[131-9^2\right]+1\)

\(=90-\left(131-81\right)+1\)

\(=91-50=41\)

\(2^4.5-\left[131-\left(13-4\right)^2\right]=16.5-\left[131-81\right]=80-50=30\)

=80-131+81+1

=31

=80-131+81+1

=31

2⁴.5- [ 131 - ( 13- 4)²]  + 2021⁰= 16.5 - [ 131 - 9² ] + 1 = 80 - 50 +1 = 31 

2⁴.5-[131-(13-4)²]

=16.5-[131-9²]

=80-(131-81)

=80-50=30

2⁴ . 5 - [131 - (13-4)² ]

= 2⁴ . 5 - [131 - 9² ]

= 2⁴ . 5 - 50

=80 - 50

= 30

=30 ai ra ket qua the la dung zui

\(2^4.5-\left[131-\left(13-4\right)^2\right]\)

\(=16.5-\left(131-9^2\right)\)

\(=80-50\)

\(=30\)

   2⁵ . 5 - [ 131 - (13 - 4)² ]

= 32 . 5 - [ 131 - (13 - 4)² ]

= 32 . 5 - [ 131 -     9²     ]

= 32 . 5 - [ 131 -    81      ]

= 32 . 5 -         50

= 160    -         50

=          110

\(2^4.5-\left[131-\left(13-4\right)^2\right]\)

\(=2^4.5-\left(131-9^2\right)\)

\(=2^4.5-\left(131-81\right)\)

\(=2^4.5-50\)

\(=16.5-50\)

\(=80-50\)

\(=30\)

2⁴.5-[131-(13-4)^2]

=2⁴.5-[131-81]

=16.5-50

=30

\(2^4.5-\left[131-\left(13-4\right)^2\right]\)

\(=2^4.5-\left[131-9^2\right]\)

\(=2^4.5-\left[131-81\right]\)

\(=2^4.5-50\)

\(=16.5-50\)

\(=80-50\)

\(=30\)