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:
x =14
Step-by-step explanation:
14x+24=18x-32
Subtract 14x from each side
14x-14x+24=18x-14x-32
24 = 4x -32
Add 32 from each side
24+32=4x-32+32
56 = 4x
Divide each side by 4
56/4 = 4x/4
14=x
Answer:
27
Step-by-step explanation:
The equation is a onestep equation, so in order to find the variable, follow these steps:
d - 4 = 23
In order to isolate the variable or get the variable by itself, you need to get rid of the constants around it or the numbers without a variable. In order to do that for this equation, you'll need to do the inverse of subtracting 4, which would be adding four to both sides.
Adding 4 to positive 23 will give you the answer of 27;
d = 27
Therefore, the variable d equals 27
Hope this helps!
B is definitely the answer
I believe the answer is 5 because if however many times you can multiply 2.5 into 12.5, you get the answer of 5.
