Work. Do Not Solve

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.
-Roberto invested some money at 6%, and then invested $5000 more than twice this amount at 12%. His total annual income from the two investments was $4500. How much was invested at 12%?

A) $26,000
B) $31,000
C) $3100
D) $15,000