Answer:
D) 
Step-by-step explanation:
Given: 
Use Exponent Rule: 
Use Addition Rule: 
For this case we must algebraically rewrite the given expression. So:
x: It is the variable that represents an unknown number
"double a number" is represented as: 
"6 less than double a number" is represented as: 
So, the final expression is: 
If we want to rewrite the expression in an equivalent way, we take common factor 2:

Asnwer:

Equivalent expression: 
Answer:
She incorrectly multiplied 15 X 1/4
Step-by-step explanation:
Answer: The maximum possible value of y is 30 ;)
Answer:
x=15
Step-by-step explanation:
21-6=15
-4x+y=-5x-y=15
x+y=-y=15
x=15