Đặt 

= 13,5 × 1420 + 13,5 × 780
= 13,5 × 1420 + 780
= 13,5 × 2200
= 29700

= 3 + 27 + 6 + 24 + 9 + 21 + 12 + 18 + 15
= 30 + 30 + 30 + 30 + 15
= 30 × 4 + 15
= 120 + 15
= 135

\(\Rightarrow\)\(\frac{29700}{135}\)

\(\frac{\text{5,4:0,4x1420+4,5x780x3}}{3+6+9+12+15+18+21+24+27}\)=220

\(\text{13,5 .1420 + 4,5 .780 .3}\\ =13,5.1420+13,5.780\\ =13,5\left(1420+780\right)\\ =13,5.2200\\ =29700\)

\(13,5\times1420+4,5\times780\times3\) 

\(=13,5\times1420+13,5\times780\) 

\(=13,5\times\left(1420+780\right)\) 

\(=13,5\times2200\) 

\(=29700\)

\(5,4:0,4\times1420+4,5\times780\times3\)

\(=13,5\times1420+13,5\times780\)

\(=13,5\times\left(1420+780\right)\)

\(=13,5\times2200\)

\(=29700\)

\(3+6+9+12+15+18+21+24+27\)

\(=\left(3+27\right)+\left(6+24\right)+\left(9+21\right)+\left(12+18\right)+15\)

\(=30+30+30+30+15\)

\(=30\times4+15\)

\(=120+15\)

\(=135\)

\(\frac{13,5\times1420+4,5\times3\times780}{3+6+9+...+27}\)

\(=\frac{13,5\times1420+13,5\times780}{\left(27+3\right)\times9:2}\)

\(=\frac{13,5\times\left(1420+780\right)}{30\times9:2}\)

\(=\frac{13,5\times2200}{270:2}\)

\(=\frac{29700}{135}=220\)

khong hieu

135 x 1420 + 4,5  x 780x 3   /    3 + 6 + 9 +....+ 27

=220 nhé

chúc bạn học tốt

mình trả lời rồi đó

13,5 x 1420 + 4,5 x 780 x 3 phần 3 + 6 + 9 + .......... + 24 + 27

=220 

chúc bạn hoc tốt nhé

\(=\frac{135\cdot142+45\cdot78\cdot3}{3\left(1+2+3+...+8+9\right)}=\frac{3\cdot45\left(142+78\right)}{3\cdot\left(\frac{9\cdot10}{2}\right)}=220\)

ko biết