Answer:
The right answer is 10 words.
Step-by-step explanation:
As Lena needs to memorize 30 words for Spanish class and she has memorized one-third of 30 then she memorized 10 words out of 30 words till now because one-third of 30 is 10(30/3= 10).
So from this, it can be a calculated that 2/3 word is left for memorization and 2/3 of 30 is 20(30/3*2). So Lena is left with 20 words to be memorized for the Spanish class. Therefore the correct answer to this question is 10.