The answer is the option C and the option D, which are:
C. Double the number of pages in the book.
D. The age of my friend.
The explanation for this problem is shown below:
By definition, a variable is an unkown quantity. In the Option A the quantity is given: 
seconds in a minute. In the option B you know the quantity too, which is 
years old. But the option C and the option D does not give any quantity, you don't know the number of pages in the book or the age of the friend yet. Therefore, the answer is the options C and D.
Answer:
1st problem: b) 
2nd problem: c) 
Step-by-step explanation:
1st problem:
The formula/equation you want to use is:
where
t=number of years
A=amount he will owe in t years
P=principal (initial amount)
r=rate
n=number of times the interest is compounded per year t.
We are given:
P=2500
r=12%=.12
n=12 (since there are 12 months in a year and the interest is being compounded per month)
Time to clean up the inside of the ( ).
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2nd Problem:
Compounded continuously problems use base as e.
P is still the principal
r is still the rate
t is still the number of years
A is still the amount.
You are given:
P=2500
r=12%=.12
Let's plug that information in:
.
Answer:
the answer is actually study and you would know
Step-by-step explanation:
Answer:
B
Step-by-step explanation:
Here, we want to choose the equation representing the time it will take if they worked together
Let the amount of tasks to be done be t
pedro will work at a rate of t/3
Camela will take t/2
So the joint rate will be
t/2 + t/3
This joint rate will be equal to 1
Thus, we have
t/2 + t/3 = 1
State the given in the question
Given that the sum of a number and 3 is subtracted from, the result is 5
State what is to be found in the question
We are to find the number. In other to achieve this, we would follow the steps below:
Step 1: Represent the number with an unknown
Let x represent the number
Step 2: Interpret the given statement mathematically
If x is the number, then the sum of the number and 3 would be
Then the sum of a number and 3 subtracted from 10 would be
Finally, when the sum of a number and 3 subtracted from 10, the result is 5, would be
Step 3: Solve for x in the mathematical interpretation of the given statement
The value of x is as calculated as shown below:
Hence, the number is 5
