A bi-millennium means two (bi) times thousand of years (millenium), this means that a bi millennium has 2000 years in it: two thousand years.
The origin of this word is latin: because of this it also has the plural of "bimillennia" <span />
X=34.78 y= 238.8..............
I assume that you meant RS and ST are segments of RT. If that is true then:
RS+ST=RT, using the values for these given...
8y+4+4y+8=36 combine like terms on left side
12y+12=36 subtract 12 from both sides
12y=24 divide both sides by 12
y=2
Answer: 3.97000947 × 10^4
K is the right answer for the problem!