Answer:
11 years old
Step-by-step explanation:
If four brothers have the average age 6, then the sum of their ages is

years.
Let x years be the age of sister. If four brothers and their sister have the average age 7, then

Multiply this equation by 5:

The sister is 11 years old.
Answer:
x = -4
Step-by-step explanation:
3x + 3 +9 = box
3x = -12
3x/3 = -12/3
x = -4
Answer:
D. 52
Step-by-step explanation:
Add 85 and 45 to get 130.
6.2n-3.7n=130
Subtract 3.7 from 6.2
2.5n=130
divide 130 by 2.5 to find n
N=52
Answer:
4.5 hours
Step-by-step explanation:
So, let's write a function p(x) which represents the total cost.
Let's let x represent the amount of hours.
The cost of a piece is a constant 10.
And there is a $8 fee per hour. In other words:

We spent a total of $46.
So, substitute in 46 for p(x) and solve for x:

Subtract 10 from both sides:

Divide both sides by 8:

Reduce:

So, we spent about 4.5 hours.