8. When you’re making subsets, you have two options for each element in the original set: you can either include it or not. This gives you 2 x 2 x 2 = 8 possible ways you can put a subset together from the three elements in {3, 4, 5}.
Answer:
For the given expression: 
Step-by-step explanation:
Here, the given expression in statement form is given as:
5 X minus Y equals 6 + negative 2 X plus Y = 8
Now, converting the given statement mathematically, we get:
5X - Y = 6 + (-2X) + Y = 8
Now, considering first and the last terms,we get:
5 X - Y = 8 .... (1)
and , considering second and the last terms,we get:
6 + (-2X) + Y = 8 or, -2X + Y = 2 ......... (2)
Adding (1) and (2) , we get:
5 X - Y - 2 X + Y = 8 + 2
or, 3 X = 10
or, X = 10/3 = 3.34
Now, 5X - Y = 8
or, 
Hence, for the given expression:

4 is the GCF.
Explanation:
4x3=12
4x5=20
5 Isn’t a factor of 12, and 6 isn’t a factor of 20. Each number above doesn’t work, so the greatest common factor of the numbers 12 and 20 must be 4.
1/2 and 1/6 because there is heads and tails and to get probability of tails it is 1/2 and you can get 6 only one time so 1/6