Question 258519
First we start with the value of coins equation:
(i) 5N + 10D = 100
Second, we have the number of coins equation:
(ii) D = 2N
By substitution, we get
(iii) 5N + 10(2N) = 100
solving for N, we get
25N = 100
N = 4
This means that D =8.