4x51x7+2x86x7+12x2x7=
(4 x7)x51+(2x7)x86+(2x7)x12=
28x51+14x86+14x12=
14x2x51+14x86+14 x12=
14x102+14x86+14x12=
14x(102+86+12)=
14x200=
2800
4x51x7+2x86x7+12x2x7
(4 x7)x51+(2x7)x86+(2x7)x12
28x51+14x86+14x12
14x2x51+14x86+14 x12
14x102+14x86+14x12
14x(102+86+12)
14x200
2800
=4x51x7+2x86x7+12x2x7
=(4 x7)x51+(2x7)x86+(2x7)x12
=28x51+14x86+14x12
=14x2x51+14x86+14 x12
=14x102+14x86+14x12
=14x(102+86+12)
=14x200
2800
4x51x7+2x86x7+12x2x7
=(4 x7)x51+(2x7)x86+(2x7)x12
=28x51+14x86+14x12
=14x2x51+14x86+14 x12
=14x102+14x86+14x12
=14x(102+86+12)14x200
=2800
hok tốt