You have 50 coins, all quarter's and dimes. How would you know how many of each coin and come up with a total of 11.15$-?

Answer 1

so, why do you say "quarter's" and not "dime's"?

Rule of thumb: MOST plurals do not include an apostrophe!

Answer 2

I would know how many of each by solving:
q+d = 50 and
25q + 10d = 1115

go for it

Answer 3

And why are you placing the dollar sign after the number? It should read ~~> $11.15 (or whatever the correct answer is).