PLEASE HELP AND EXPLAIN HOW TO DO THIS IM SO CONFUED Mr. Jacobs is going to make a histogram of the test scores from the last math test he gave. He plans to first organize the data into a stem-and-leaf plot and then make the histogram from the stem-and-leaf plot. The test scores are listed below.

79, 82, 65, 61, 94, 97, 84, 77, 89, 91, 90, 83, 99, 71, 68, 77, 87, 85

Which of the following expressions could be used to find how many students scored less than a 90 on the test?

3 + 4
4 + 6
3 + 4 + 6
3 + 4 + 6 + 1