Although perhaps not intended by the brother, what
wisdom might this image
conjure in reference to the
cactus itself for Trysdale in O.
Henry's "The Cactus"?
"Very well. It's a tropical
concern. See hundreds of 'em
around Punta every day."
A. The desert is no place for a lover.
B. There are many other brides out there
with which to fall in love.
C. They may not give fruit, but they are
plentiful.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.

18≥1.5x

then you're going to want to divide 18 by 1.5. this equals 12. so the answer would be 12.

aka, you can buy 12 peppers, at most.