Answer:
Step-by-step explanation:
i can help
Step 1
4( − 11) = 15 − 4 Solving
Step 2
4( − 11) = 15 − 4 Simplify
15-4
-44=11
Answer
Unique solution
Hope this helps
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.
So you will have to find the difference between each number so 6--2=8
and 8--2=10. So then I'm guessing you have to round 8 to 10. Sorry if this isn't all correct.