The "one head and one tail" would be my best guess because you get one of each outcome, whereas the other two outcomes are two of the same outcome.
The answer is -8. Do you need an explanation?
You have to solve this algebraicly.
To do this set up the proportion and add x to each term.
You get 4x and 7x
Set this equal to 33
4x+7x=33
Combine like terms and get 11x=33
Divide by 11
x=3
Now go back to 4x and 7x
Multiply them by x and get 12(4×3=12) and 21(7×3=21)
One group is 12 and the other is 21.
