Question 8013
You just need these "set up" and not solved, right?
You choose variables for the number of dimes and nickels. Let's use d and n.
So since a d is worth 10 cents and an n is worth 5 cents, 
10d + 5n = 105
Also, n is 6 more than d. That is, if we knew how many n there were, we could find how many d there were by subtracting 6. So,
n - 6 = d
You put this value for d in the first equation and get
10n - 60 + 5n = 105
Solve that and you know how many nickels there were.
Then subtract 6 and you know how many dimes there were.
I say "were" because by now Maria has spent them!

Your second question just reads like algebra. Let n be the number.
So, three times the number and then five more is fourteen.
3x + 5 = 14