Question

(9x7+8x9-15x9):(1+3+5+7+ ....+17+19)

Answer 1

\(9\times7+8\times9-15\times9.\\ =9\times\left(7+8-15\right)=9\times0=0.\)

\(\Rightarrow\left(9\times7+8\times9-15\times9\right):\left(1+3+5+7+...+17+19\right).\\ =0:\left(1+3+5+7+...+17+19\right).\\ =0.\)

Answer 2

\(=\left(15\cdot9-15\cdot9\right):\left(1+3+...+17+19\right)=0\)

Answer 3

=9×(7+8-15)=9×0=0

=0:(1+3+5+7+...+17+19)

=0