O.k. I'm 42 trying to help my nephew with algebra and lets just say it's been awhile....

Total money $ 101.25
45 more dimes than nickels
3 times as many quarters as dimes.

How many nickels, dimes & quarters?

3 answers

d times
n nickels
q quarters

d = (n + 45)
q = 3 d so q = 3(n+45)

5 n + 10 d + 25 q = 10125

n + 2 d + 5 q = 2025
so
n + 2 (n+45) + 15 (n+45) = 2025

n + 17(n+45) = 2025
18 n + 765 = 2025
18 n - 1260
n = 70 nickels
you can get the rest now
Got it. Man that felt good to actually solve a problem after all these years.
Hey, at least you are not 74 and trying to help :)