7. 233
8. 4
9. 6
10. 5
11. 4
12. 7
13. 7
When a set of objects are chosen from a larger set in which the order of the object doesn't matter, we call this combination. Otherwise if the order of selection would matter this would be called a permutation.
Probability is the likelihood of selecting a particular specified object in from a specified group of objects.
Therefore our answer is B.
Answer: c = 2h + 15
Step-by-step explanation: Each house (h) adds 2 cats. We represent that with 2h. Then we add the constant 15 on the ground as +15.