Answer:
10
Step-by-step explanation:
Let c = sum of ages of all children.
mean age of all children = c/15 = 7
c = 15 * 7 = 105
The sum of the ages of all children is 105.
Let b = sum of ages of the 9 boys.
mean age of boys = b/9 = 5
b = 9 * 5 = 45
The sum of the ages of the boys is 45.
The sum of the ages of the girls is c - b.
c - b = 105 - 45 = 60
The number of girls is 15 - 9 = 6
mean age of girls = (sum of ages of the girls)/(number of girls) =
= 60/6 = 10
answer:
x = - 9/2
y = -10
Step-by-step explanation:
make both equations look like y =
2x-3y=21 -> -3y= -2x+21 -> y = (-2x+21)/-3 -> y = 2/3x - 7
-6x + 2y = 7 -> 2y = 6x + 7 -> y = 3x + 7/2
now make the equations equal to each other (since they both equal y)
get x
2/3x - 7 = 3x + 7/2
-7 -7/2 = 3x - 2/3x
-14/2 -7/2 = 9/3x - 2/3x
-21/2 = 7/3x
(3/7) -21/2 = x
x = (3/7) -21/2
x = - 63/14
x = - 9/2
put it back in an equation to get y
y = 3x + 7/2
y = 3(-9/2) + 7/2
y = -27/2 + 7/2
y = -20/2
y = - 10
brainly.com/question/12203001
We would need the data of their classmates scores to complete this answer
