A. two 7-sided fair dice are tossed simultaneously. what is the probability of getting two sevens? b. two 7-sided fair dice are tossed simultaneously. what is the probability of getting three sevens?

A).
The first cube can land in any one of 7 ways. For each of those . . .
The second cube can land in any one of 7 ways.

Total number of possible results = (7 x 7) = 49 .

Number of successful results (both land on 7s) = 1

Probability = 1/49 =  2.04% .

B).
This is a trick question.
Two dice can only show 2 numbers at a time.
The probability of any combination of 3 numbers is zero.