Based on the box-and-whisker plot shown below, what value is the 75th percentile?

Alright, so the dot on the left is the start, the start of the box is the 25th percentile, the line inside of it is the median, the end of the box is the 75th percentile, and the dot on the right is the 100th percentile. The 75th percentile, or the end of the box, is 20

The answer is B
You have to find the missing sides, so 78-32=46 & 54-18=36
46 & 36 are your missing sides now you can added up all the sides 78+32+46+54+18+36=264