Problema Solution
A child is collecting state quarters and new $1 coins. If she has a total of 25 coins, and the number of quarters is nine more than the number of dollare coins, how many of each tpye of coin does she have?
Answer provided by our tutors
D+Q=25, D is for Dollar coins and Q is for quarters
Q+9=D
use substitution to solve for Q: Q+Q+9=25 --> 2Q+9=25 --> 2Q=16 --> Q=8
solve for D using substitution: 8+D=25 --> D=17