\(\frac{13,5\times1420+4,5\times3\times780}{3+6+9+...+27}\)
\(=\frac{13,5\times1420+13,5\times780}{\left(27+3\right)\times9:2}\)
\(=\frac{13,5\times\left(1420+780\right)}{30\times9:2}\)
\(=\frac{13,5\times2200}{270:2}\)
\(=\frac{29700}{135}=220\)
135 x 1420 + 4,5 x 780x 3 / 3 + 6 + 9 +....+ 27