a) 386 × 7 - 386 × 5
= 386 × ( 7 - 5 )
= 386 × 2
= 772
b) 492 + 492 × 135 - 492 × 36
= 492 × ( 1 + 135 - 36 )
= 492 × 100
= 49200
c) 8 × 864 + 864 × 2
= 864 × ( 8 + 2 )
= 864 × 10
= 8640
d) 679 + 679 × 123 - 679 × 24
= 679 × ( 1 + 123 - 24 )
= 679 × 100
= 67900
P/s: cái ý còn lại bạn làm tương tự nha
A/ 386.7-386.5
=386.(7-5)
=386.3
=1158
B/492+492.135-492.36
=492.1+492.135-492.36
=492.(1+135-36)
=492.100
=49200
C/8.864-864.2
=864.(8-2)
=864.6
=5184
D/679+679.123-679.124
=679.1+679.123-679.124
=679.(1+123-124)
=679.0
=0
E/2912.94-1456.44.2
=2912.94-2912.44
=2912.(94-44)
=2912.50
=145600
G/245.327-245.18-9.245
=245.(327-18-9)
=245.300
=73500
K mình nhé!