Answer:0.000810
Step-by-step explanation:
Given
A committee of 3 members is formed using
5 Admin, 34 teachers, and 4 staff
Favorable outcomes are selecting 3 members as Administrators
total members =5+34+4=43
Probability is given by


If you're asking for the model for the second problem (I didn't see any unsolved), here it is!
Let the value of the number be represented as x.
Then, write out an equation;
3x=2x+3 <--- Solve for x now
3x-2x=3
x=3
Therefore the number is 3.
Hope I helped :)