Let us suppose that 'm' cookies and 'n' brownies were baked.
Since, Helen baked 31 items in total.
So, m+n = 31 (Equaion 1)
So, m = 31-n
Now, since cookies are sold for 95 cents, and the brownies sold for 60 cents.
Since, 1 $ = 100 cents
So, cookies are sold for $0.95, and the brownies sold for $0.60.
Helen sold the cookies and brownies at $23.85
So, 0.95m + 0.60n = 23.85 (Equaion 2)
Substituting the value of 'm' in equation 2, we get as
[tex]0.95(31-n)+0.60n = 23.85[/tex]
29.45 - 0.95n +0.60n = 23.85
-0.35n = -5.6
So, n = 16
Since, m = 31-n
m = 31-16
m = 15
So, Helen sold 15 cookies and 16 brownies.