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.
 
        
             
        
        
        
Make each fraction have a like denominator
7/9 *  8/8= 56/ 72
7/8 * 9/9 = 63/72
18 + 14 + (56+63)/72
32 + 119/72
32 + 1 + 47/72
33 and 47/72
 
        
                    
             
        
        
        
Answer:
y= 3x+5
Step-by-step explanation:
start with the linear equation formula
y= mx+b
indentify what you already have.
x= -1 and y= 2 and m(slope)= 3
We are solving for b, so plug in what you have.
2= 3(-1)+b
Simplify.
2= -3+b
Add 3 on both sides.
5= b
Rewrite your equation with the x and y values.
y= 3x+5
 
        
             
        
        
        
(0,7) would be located on the y axis
        
             
        
        
        
Answer:
8 students 
Step-by-step explanation:
72 slices of pizza and 80 cookies were purchased after a school program
Each student will get an equal numbert of both pizza and cookies
72/8
= 9
80/8
= 10-1
= 9
Hence 8 students can attend the after tutoring program