1) The National Aeronautics and Space Administration (NASA) keeps track of how man missions their sh

1) The National Aeronautics and Space Administration (NASA) keeps track of how man missions their shuttles have completed.begin{tabular}{|l|c|}hline multicolumn{2}{|c|}{ (1) NASA shuttle missions } \hline (1)) Shuttle name & (1)) Number of missions \hline (1)) Challenger & 9 \hline (1) Discovery & 38 \hline (1)) Atlantis & 32 \hline (1)) Endeavour & 34 \hline (1)) Columbia & 27 \hlineend{tabular}What fraction of NASA shuttle missions were carried out by Discovery or Atlantis?Simplify your answer.
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