Given:
and 
.
To find:
The combinations without repetition are possible if and .
Solution:
Combination of selecting r item from total n items is:
We have and . By using the above formula, we get
Therefore, the correct option is D.
By the number amount of the books like 1 biology and 2 mathematic book and 3 different novels or my grade
Step-by-step explanation:
1. Choose arbitrary points A and B in the plane and draw segment AB.
2. Raise a perpendicular m to AB at A.
3. Raise a perpendicular n to AB at B.
4. Choose an arbitrary point C on line n.
5. Drop a perpendicular from point C to line m. Let D be the foot of this perpendicular.
6. Then quadrilateral ABCD is a rectangle.
The equation you want to use is this:
10x = 530 10 pages for x days
x = 530/10 530 pages divided by 10 pages
So the answer is,
53 days
