Answer:
x = 7
Step-by-step explanation:
angles 2 and 3 form a straight angle and are supplementary, that is they sum to 180°, hence
∠2 + ∠3 = 180 ← substitute values
20x - 1 +4x + 13 = 180
24x + 12 = 180 ( subtract 12 from both sides )
24x = 168 ( divide both sides by 24 )
x = 7
