You can
put this solution on YOUR website!
The first equation is a COIN equation:
D + N = 15
The second equation is a money equation:
$.10D + $.05N = $1.30
or thinking of it in pennies,
10D + 5N = 130
So you have the systen of equations:
Can you solve that system? If not post again asking how.
Solve that and get D=11, N=4
11 dimes is $1.10 and 4 nickes is $.20 a total of $1.30, so it checks.
Edwin