Step-by-step explanation:
Given: 
Derivative of a power function
:

Therefore,

Answer:
x=4
Step-by-step explanation:
-(7-4x)=9
-7+4x=9
4x=16
x=4
Answer:
Second option:
Step-by-step explanation:
Let be "x" the number of candy bars Brady sold on Saturday.
For this exercise you need to analize the information provided in the exercise.
According to the information provided, Brady gets paid $2 for every candy bar he sells. This can be expressed as:

You know that Brady made a total of $90 on Saturday; this mean the product of
is 90.
Based on this, you can write the following equation that represents the number of candy bars Brady sold on Saturday:

Observe that this matches with the second option.
Explanation:
Kadisha's method works because 15% is 3 times 5%, and both amounts are computed on the amount of the bill before tax is added.
Answer:
Total number of orange trees = 77 trees
Step-by-step explanation:
Given:
Total number of rows = 15
Total number of cherry rows = 4
Number of trees in each rows = 7
Find:
Total number of orange trees
Computation:
Total number of orange trees = [Total number of rows - Total number of cherry rows][Number of trees in each rows]
Total number of orange trees = [15 - 4]7
Total number of orange trees = [11]7
Total number of orange trees = 77 trees