Write the Word or Phrase That Best Completes Each Statement $$\begin{array} { r } - 9 x ^ { 2 } + 8 y ^ { 2 } = 36 \\x - 6 y = - 7\end{array}$$

Essay

Write the word or phrase that best completes each statement or answers the question.
Which method should be used to solve the system? Explain your answer, including a description of the first step.
$$\begin{array} { r } - 9 x ^ { 2 } + 8 y ^ { 2 } = 36 \\x - 6 y = - 7\end{array}$$