Answer:
18
Step-by-step explanation:
3x+1=55
(alternate angle theorem)
3x=55-1
3x=54
x=54/3
x=18
d
3x + 1 and 55 are alternate angles and congruent, thus
3x + 1 = 55 ( subtract 1 from both sides )
3x = 54 ( divide both sides by 3 )
x = 18 → d
