Răspuns :
{[(3+a) x3 x3]x3+3}x3+3=100:2x4+217
{[(a+3)x3x3]x3+3}x3+3=417
{[(a+3)x3x3]x3+3}x3=417-3=414
[(a+3)x3+3]x3+3=414:3=138
[(a+3)x3 x3]x3=138-3=135
(a+3)x3 x3=135:3=45
(a+3)x3=45:3=15
a+3=15:3=5
a=5-3
a=2
{[(a+3)x3x3]x3+3}x3+3=417
{[(a+3)x3x3]x3+3}x3=417-3=414
[(a+3)x3+3]x3+3=414:3=138
[(a+3)x3 x3]x3=138-3=135
(a+3)x3 x3=135:3=45
(a+3)x3=45:3=15
a+3=15:3=5
a=5-3
a=2