Answer:
23 years old
Step-by-step explanation:
Let x = age of younger sibling.
Then, the age of the older sibling is x + 9.
x + x + 9 = 55
2x = 46
x = 23
Answer: 23 years old
For sake of convenience, reverse the series, then it would be:
21,19,17.....7
a=21, d = -2,
s(4) = 4/2 (21+15)
s(4)=2(36)
s(4) = 72
Each side of the rhombus is 121 feet
