math
posted by Bob .
a person has $4 in nickles, quarters, and dimes. there is a total of 36 coins altogether. the number of quarters is 4 less then the number of dimes. Algerbaicly determine the number of each type of coin using a system of 3 equations with 3 variables.

a).05N+.10D+.25Q=4
b)N+D+Q=36
Q=D4
c) DQ=4