Brainliest + ! can you show me the proper calculation for this? since i got it wrong?

  Well the reason your answer is 15 is because, mode is described as the value in the data that occurs most often. Meaning if 50% of students said that they started school at 15, then that is the value that occurs most often in your data.

-3/2

Step-by-step explanation:

Let x = the integer:

2x^2 - 18 = 9x

2x^2 - 9x - 18 = 0

Now either factor that or use the quadratic formula if you're lazy like me.

x = -3/2 and 6, so x must be 6 because it has to be an integer.