Write the Word or Phrase That Best Completes Each Statement $\begin{array} { l } x ^ { 2 } + 8 y ^ { 2 } = 25 \\- 7 x ^ { 2 } - 5 y ^ { 2 } = 100\end{array}$

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.
- $\begin{array} { l } x ^ { 2 } + 8 y ^ { 2 } = 25 \\- 7 x ^ { 2 } - 5 y ^ { 2 } = 100\end{array}$