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:
It is, D
Step-by-step explanation:
Your welcome for raising your test score
If the equation is in the form of y = mx + C, where m and C are real numbers, the slope (which means gradient) of the line is the coefficient of x (I.e. the number to the left of x in simple language), which is m.
In this case, m = 54 and C = -13pie. Both are real numbers, which means that this equation satisfies the form of y = mx + C
m is the coefficient of x, which is 54. 54 is the gradient of this line, which means that for every 54 y-axis units the line increases, the line increases 1 x-axis unit.
Hope this helps! :)
Yes it is also a 50% decrease.