Question

Calculati n
{{(n x 2+40 x 20):23+12] x 6-6}:30= 15.

Answer 1

$\rule{0.2}{0.2}_{ \{[(n\cdot2+40\cdot20):23+12]\cdot6-6\}:30=15\bigg|_{\cdot30} \Rightarrow [(n\cdot2+40\cdot20):23+12]\cdot6-6=450\bigg|_{+6} \Rightarrow$

$\it \rule{0.2}{0.2}_{\Rightarrow \ [(n\cdot2+40\cdot20):23+12]\cdot6=456\bigg|_{:6}\ \Rightarrow \ (n\cdot2+40\cdot20):23+12=76\bigg|_{-12} \Rightarrow (n\cdot2+40\cdot20):23=64\bigg|_{\cdot23} \Rightarrow}$

$\it \rule{0.2}{0.2}_{\Rightarrow n\cdot2+800=1472\bigg|_{-800} \Rightarrow n\cdot2=672\bigg|_{:2} \Rightarrow \bf n=336}$