Work. Do Not Solve

Multiple Choice

work. Do not solve.
-5x + 9y = -12
-4x - 4y = -32
A) Substitution B) Addition
Answer: B
Write the word or phrase that best completes each statement or answers the question.
-Walt made an extra $7000 last year from a part-time job. He invested part of the money at 10% and the rest at 9%. He made a total of $680 in interest. How much was invested at 9%?

A) $5000
B) $7000
C) $3500
D) $2000