Maria has $\$2.43$ in quarters and pennies in her wallet. She has twice as many pennies as quarters. How many of each type of coin does she have?

Let $q$ be the number of quarters. Then $2q$ is the number of pennies. Total value: $0.25 q + 0.01 (2q) = 2.43$. Multiply out: $0.25 q + 0.02 q = 2.43$. Combine: $0.27 q = 2.43$. Divide: $q = 9$. So $q = 9$ quarters and $2q = 18$ pennies. Check: $9 (0.25) + 18 (0.01) = 2.25 + 0.18 = \$2.43$ ✓. Trap A gives $7$ quarters → total $1.75 + 0.14 = 1.89 \ne 2.43$. Trap D swaps the *twice as many* relation onto quarters instead of pennies.