Answer:
x = 40
Step-by-step explanation:
Since FG and HI are parallel and BC is a transversal, then
∠ GBE and ∠ GBE are same side interior angles and are supplementary, thus
3x + 20 + x = 180, that is
4x + 20 = 180 ( subtract 20 from both sides )
4x = 160 ( divide both sides by 4 )
x = 40