{[(3×n+5)×3+5]×3+5}×3+5=281/-5
{[(3×n+5)×3+5]×3+5}×3=276/÷3
[(3×n+5)×3+5]×3+5=92/-5
[(3×n+5)×3+5]×3=87/÷3
(3×n+5)×3+5=29/-5
(3×n+5)×3=24/÷3
3×n+5=8/-5
3×n=3
n=3÷3
n=1