What is -7 + -9 A. -16 B. -2 C. 2 D. 16
2 answers:
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Answer:
155
Step-by-step explanation:
Number of math books = 7
Number of science books = 5
Number of engineering books = 10
We need to find the number of ways to pick two books with different subjects.
Solution :
We will use combination here .
If we need to choose r objects from total n objects ,
So, number of ways to pick two books of same subjects =
Also, number of ways to select any two books =
Therefore , number of ways to pick two books with different subjects =
number of ways to select any two books - number of ways to pick two books of same subjects = 231 - 76 = 155