Two classmates are preparing research papers and are organizing their information on index cards.

keiko is using 3 in. x 5 in. cards.

william is using 4 in. x 6 in. cards.

a. set up a proportion to determine if the students are using index cards that are similar. are they similar?

b. a third student, joel, is writing his information on paper that measures 12 in. x 8 in.

is this similar to either keiko's or william's cards? show your setup and work to support your answer.