Answer:
x + 2x = 109
Step-by-step explanation:
Divide both sides by -6.2:
-50 = f
Answer: The average was 9 years old find the average age of both groups is 10 years old.
Step-by-step explanation:
Formula foe average : 
Given : The first group of students consists of 10 and their average age was 13 years old.
i.e.
(1)
The next group consisted of 30 students and their average was 9 years old.
i.e.
(2)
Then from (1) and (2) , the sum of both groups (first group and next group )students = 130+270 =400
Combined students of both groups (first and next group )= 10+30=40
Now , the average of both groups =

Hence, the average was 9 years old find the average age of both groups is 10 years old.
Answer:
independent or complementary
Step-by-step explanation:
Not sure but that's my best guess.
2+a / 2 = 4 and b+6 /2 = 10
2+a=8. and. b+6 = 20
a=6. and. b=14
(a,b) , the other endpoint, is thus (6,14)