Answer:
a
Step-by-step explanation:
I think I only know the answers to 4 and 5 :)
5 = 9a + 12b
4 = subtraction
Answer:
I think the answer is 10
Step-by-step explanation:
If the surface is 0, and the diving board is the same distance as the bottom of the pool is from the surface, which is -10, then the diving board should be 10.
Answer:
The people can seat themselves in 20160 different ways.
Step-by-step explanation:
Arrangements of n elements:
The number of arrangements of n elements is given by the following formula:

In this question:
For the first seat, that is, the driver seat, 4 possible people can sit.
For the remaining 7 seats, the number of ways in which the people can sit is an arrangement of 7 elements. So

The people can seat themselves in 20160 different ways.