làm câu 6,7,8,9,10 thôi nha mấy câu khác không cần

7)

64x57+64x43-2400

=64x(57+43)-2400

=64x100-2400

=6400-2400

=4000

8)43x78-43x48+30x80-30x23

=43x(78-48)+30x80-30x23

=43x30+30x80-30x23

=30x(43+80-23)

=30x100=3000

9)2^3x17-2^3x14

=(2^3-2^3)x(17-14)

=0x3=0

10)(3^18x4+5x3^18):3^18

=3^18x(4+5):3^18

=3^18x9:3^18

=3^18x3^2:318=3^18+2-18=3^2

6)31x175-31x50+69x125

=31x(175-50)+69x125

=31x125+69x125

=125x(31+69)
=125x100

=12500