Answer:
Jill identified 8 species of plants. The number of plants identified is unknown.
Step-by-step explanation:
We are apparently to assume that the species Jill identified were either plants or animals. Hence 2/5 of those identified were plants. That makes the number of plant species ...
(2/5)(20) = 8 . . . . plant species identified.
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The question asks how many plants (not plant species) Jill identified. The problem statement does not give us sufficient information to answer that question.