Answer:
x = 11.25
Step-by-step explanation:
-6 = 0.8x - 15
Add 15 to both sides;
-6 + 15 = 0.8x - 15 + 15
9 = 0.8x
Divide both sides by 0.8;
x = 11.25
A fair coin just means 50% heads 50% tails. so the sample is still 50% heads 50% tails.
I believe the answer is C