\(A=\frac{13,5.1420+4,5.780.3}{3+6+9+...+24+27}\)

\(=\frac{13,5.1420+\left(4,5.3\right).780}{\left(3+27\right)+\left(6+24\right)+\left(9+21\right)+\left(12+18\right)+\left(15+15\right)}\)

\(=\frac{13,5.\left(1420+780\right)}{30.5}\)

\(=\frac{13,5.2200}{150}\)

\(=\frac{29700}{150}=198\)

Chị làm lại nhé

\(A=\frac{13,5.1420+4,5.780.3}{3+6+9+12+15+18+21+24+27}\)

\(=\frac{13,5.\left(1420+780\right)}{\left(3+27\right)+\left(6+24\right)+\left(9+21\right)+\left(12+18\right)+15}\)

\(=\frac{13,5.2200}{30.4+15}\)

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

Mk ko biết xl nhá :<<

\(A=\left(27,54.\frac{11}{16}-3.405\right):3\)

\(A=\left(\frac{15147}{800}-3.405\right):3\)

\(A=\frac{12423}{800}:3\)

\(A=\frac{4141}{800}\)

\(B=\left(\frac{1}{6}+0,1+\frac{1}{5}\right):\left(\frac{1}{6}+0,1-\frac{1}{5}\right)\)

\(B=\frac{7}{15}:\frac{1}{15}\)

\(B=7\)

\(C=\left(0,5-\frac{1}{3}+0,25\right):\left(0,25-\frac{1}{6}\right)\)

\(C=\frac{5}{12}:\frac{1}{12}\)

\(C=5\)

\(D=\frac{13,5.1420+4,5.780.3}{3+6+9+...+24+27}\)

              Số số hạng từ 3 đến 27 là:
                      (27-3):3+1=9(số hạng)

              Tổng dãy số từ 3 đến 27 là:

                       (27+3)x9:2=135

\(D=\frac{13,5.1420+13,5.780}{135}\)

\(D=\frac{13,5.\left(1420+780\right)}{135}\)

\(D=2200\)

Dấu . là dấu nhân

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

ko biết

Xét mẫu có số số hạng là : (27 - 3) : 3 + 1 = 9 (số hạng)

Ta có :

\(\frac{\frac{5,4}{0,4}.1420+4,5.780.3}{3+6+9+...+27}=\frac{13,5.1420+45.78.3}{\frac{\left(27+3\right).9}{2}}=\frac{19170+10530}{135}=\frac{29700}{135}=220\)

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

A=1498

13,5×142+4,5×78×3+1,5×80×9

=13,5×142+4,5×3×78+1,5×9×80

=13,5×142+13,5×78+13,5×80

=13,5×(142+78+80)

=13,5×300

=13,5×100×3

=1350×3

=4050