36. During rehearsal for the Founders’ Day choir
program, the director, Mrs. Mazurek, tried 3 different
configurations, each using all the choir members at the
rehearsal. One configuration was to have only rows of
12, one was to have only rows of 15, and one was to
have only rows of 20. None of these configurations
worked because for each, the last row had 1 person
less than the other rows. What was the least of the
possible numbers of choir members at the rehearsal?