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
Ok, so you automatically know that you are subtracting 6 from 10 to get 4. So, in order to figure out how it is 1/3 of that number, it is going to be multiplied by 3, getting 18. So, the number would be 18.
Answer:
The answer is:
Step-by-step explanation:
1. -30
2. 20
Answer:
4(2n-5)
Step-by-step explanation:
So we know Valerie has 5 less than double the number of brad's books. Brad has n books, so make that 2n to double it.
Because she has 5 less than that, the expression is now 2n-5. The is the total of Valerie's books.
We know that Brad has 4 times the number of Valerie's books, so just multiply that expression by 4.
The final answer is 4(2n-5).
You're welcome. :)
