1, 215 + (-38) - (-58) + 90 - 85

= 215 - 38 + 58 + 90 - 85

= (215 - 85) + (-38 + 58) + 90

= 130 + 20 + 90

= 150 + 90

= 240

2, 917 - ( 417 - 65 )

= 917 - 417 + 65

= 500 + 65

= 565

camonn

\(65\left(75+189\right)-75\left(65+189\right)\)

\(=65.75+65.189-75.65-75.189\)

\(=\left(65.75-75.65\right)+\left(65.189-75.189\right)\)

\(=0+\left(65-75\right).189\)

\(=0+\left(-10\right).189\)

\(=-10.189\)

\(=-1890\)

Đáp án cần chọn là: C

Đáp án là C

\(2\times3\times5+25\times8\times4+70+4\times2\times25\)

\(=15\times2+100\times8+70+100\times2\)

\(=30+800+70+200\)

\(=\left(30+70\right)+\left(800+200\right)\)

\(=100+100\times10\)

\(=100+1000\)

\(=1100\)

a) (-124) + 24 = -100
b) 37. 78 + 37. 22
=  37 . ( 78 + 22 )
=  37 . 100
= 3700

\(a) (-124) + 24 = -100 b) 37. 78 + 37. 22 = 37 . ( 78 + 22 ) = 37 . 100 = 3700\)

a) (- 124) + 24                                          b) 37 . 78 + 37 . 22

= - ( 124 - 24)                                              =37 . ( 78 + 22)

= - 100                                                        =37 . 100 

                                                                    3700

\(...=25x4x\left(7x3+3x4x5+2\right)=100x\left(21+120+2\right)=100x143=14300\)

14300

14300

7 x 12 x25 +3 x 16 x125 +8 x25

=7 x4 x3 x25 +3 x4 x4 x5 x25+4x2x25

=(4 x25) x(7 x3 +3 x4 x5 +2)

= 100 x (21 +60 +2)

= 100 x 83

= 8300