Answer:
a) 
b) 
Step-by-step explanation:
From the question we are told that:
3 coin are tossed
Therefore
Sample space 
Generally the sets that correspond with the result of at most one tail is therefore given as follows

Therefore
The result is at most one tail when

Answer:
Divide both sides by -1/3, Apply distributive property, add 1/3 to both sides
Step-by-step explanation:
If its confusing just replace -1/3 with a simple number such as -1, to make it make sense.
If you meant, "how many zeros are there in the standard form of 'ten divided by 3,' the answer would be, "none."
10/3 = 3.3333333333333.... This is a repeating decimal.