
Brian W. answered 08/26/19
Experienced, Knowledgable & Fun-Loving K-12 and Aviation Tutor
The question asks how many MORE students like red or green than blue. When we see the the clue words "how many more" in the question, we know we are dealing with a difference, or a subtraction problem. since we are taking the difference between red or green THAN blue, we must add together the red/green totals, and then subtract blue from them to see how many more students like red or green than blue.
RED: 228
GREEN: 154
BLUE: 293
red + green = 228 + 154 = 382 total students that like red/green together
382 - 293 = 89 students, so 89 more students like red or green more than blue.