300 cookies were ordered to start.
We can tell this because we know 12% is equal to 36. Because this is true, we can set up a proportion to solve. All proportions can be set up with the small number on top and the total on the bottom. This will help you solve for the missing number, which is in this case the total number of cookies. Let x be the total number of cookies.
Percentage/total percentage = cookies/cookies total
12/100 = 36/x
Now we can cross multiply to solve.
(100)(36) = (12)(x) ----> multiply
3600 = 12x ---> divide by 12
300 = x
To solve this problem you must use the information given in the problem above:
1. You have that he jogs
to the park and then
to the playground, then he jogs
miles to the bridge and
to his house.
2. Therefore, as you can see, Jerry completes his jog when he arrives to his house. So, he is
from his house.
Then, the answer is: 
Since the triangles are similar, all sides are proportional by the same scale factor.
The relationship between the bases 32 and 8 is 4 (32/8 = 4). This means that the smaller triangle need to be multiplied by a scale factor 4 to result in the bigger triangle.
This means that 4x + 12 is 4 times greater than 15.
The equation to solve for x can be written as:
4x + 12 = 4*15
Now just solve for x as u normally would
4x + 12 = 60
(Subtract twelve from both sides)
4x = 48
(Divide both sides by 4 to isolate x)
x = 12
I hope this somewhat helped :)
Was my explanation clear enough?