tính nhanh a, 150.19+84.67+71.84+84.12 b, 4.51.7+2.86.7+12.2.7 c,36.28+64.69+36.82+41.62 cho mk cả cách giải nha

a. 150.19 + 84.67 + 71.84 + 12.84

= 150.19 + 84(67+71+12)

= 150.19 + 84.150

=150(19+84)=150.105 = 1575

b. 4.51.7 + 2.86.7 + 12.2.7

=7(4.51 + 2.86 + 12.2)

=7(204+172 + 24)

=7.400=2800.

c. 36.28 + 64.69 + 36.82 + 41.62

=36(28+82) + 64.69 + 41.62

=36.110 + 64.69 + 41.62

=3760 + 64(70-1) + 62(10+1)

=3760 + 448-64 + 620 + 62

=3760 + 448+62+620-64

=3760 + 510 + 620 -2

=3760 + 1130-2=4890-2=4888

a) 150.19+84.67+71.84+84.12=84.(150.19.(67+71+12))

=84.(150.19.150)=84.150.19=239400

b) 4.51.7+2.86.7+12.2.7=7.((4.51)+(2.86)+(12.2))

=7.(204+172+24)=7.400=2800

c) 36.28+64.69+36.82+41.62=36.(28+82)+((64.69)+(41.62))

=36.100+(4416+2542)=3600+6958=10558