Answer:
thank youuu :))) <<<<<<<<<<<
Answer:
Step-by-step explanation:
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.

Step-by-step explanation:
find the value of the constant of proportionality k

c =total cost
d =days