{[(3xn+5)x3+5]x3+5}x3=281-5
{[(3xn+5)x3+5]x3+5}x3=276
{[(3xn+5)x3+5]x3+5}=276:3
{[(3xn+5)x3+5]x3+5}=92
[(3xn+5)x3+5]x3=92-5
[(3xn+5)x3+5]x3=87
[(3xn+5)x3+5]=87:3
[(3xn+5)x3+5]=29
(3xn+5)x3=29-5
(3xn+5)x3=24
(3xn+5)=24:3
(3xn+5)=8
3xn=8-5
3xn=3
n=3:3
n=1
