I= 1/2 prt solve for t show your work. i don't understand this.

In the following situation, determine whether you are asked to determine the number of permutations or combinations. then do the calculation how many ways are there to pick a starting five from a basketball team of twelve members? a. permutation; ps - 2520 b. combination; 1c, - 792 c. combination: 2cs - 2520 d. permutation; ps - 95040

What is the missing step in this proof ?

You deposit $5000 each year into an account earning 3% interest compounded annually. how much will you have in the account in 30 years?