Step-by-step explanation:
Sum of angles in a triangle = 180°.
Question 3:
We have 90° + 61° + (14x + 1)° = 180°.
=> 14x° + 152° = 180°
=> 14x° = 28°
=> x = 2.
Question 4:
We have 70° + 55° + (4x + 3)° = 180°.
=> 4x° + 128° = 180°
=> 4x° = 52°
=> x = 13.
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:
3/4
Step-by-step explanation:
3/4 = .75
4/10 = .40
2/5 = .40
1/3 = .33
Answer: x=-3
Step-by-step explanation:
2x-18=8x
-2x. -2x.
-18=6x
-18/6=6x/6
-3=x
Answer:
6x + y = 1
y = 1 - 6x
7x + 2(1 - 6x) = -3 substitute 1 - 6x in for y
7x + 2 - 12x = -3 combine like terms
2 - 5x = -3 subtract 2 from both sides
-5x = -5 divide by -5
x = 1