N + (3n - 15) = 101 is the equation, the answer to the equation is 29
the price of oil has increased by $0.06 during the period
you would do 3-4=-1 and then -1+7= 6
so you would be left with a gain of $0.06
hope this helps! good luck!
Answer:

Step-by-step explanation:
Area of the shaded region = area of the large rectangular - area of the small rectangle
Area of rectangle is given as l*w
Area of the large rectangle = 
Expand


Area of large rectangle 
Area of small rectangle = 


Area of small rectangle = 
Area of shaded region = 

Collect like terms


The answer should be 39/400