[ { 4 x X + 28 } x 3 + 55 ] : 5 = 35
[ { 4 x X + 28 } x 3 + 55 ] = 35 x 5
[ { 4 x X + 28 } x 3 + 55 ] = 175
{ 4 x X + 28 } x 3 = 175 - 55
{ 4 x X + 28 } x 3 = 120
4 x X + 28 = 120 : 3
4 x X + 28 = 40
4 x X = 40 - 28
4 x X = 12
X = 12 : 4
X = 3
(4*X+28)*3+55=35*5
=>(4*X+28)*3+55=175
=>(4*X+28)*3=120
=>4*X+28=40
=>4*X=12
=>X=3