7points!

i'm learning about equations with square roots & cube roots in 8th grade math. (image included)

my main question is what is this ± symbol?

The number of pages in the u.s. tax code exceeds the number of pages in the king james bible by 18,528. the combined number of pages in the tax code and the bible is 21,472

The median of a data set is the measure of center that is found by adding the data values and dividing the total by the number of data values that is the value that occurs with the greatest frequency that is the value midway between the maximum and minimum values in the original data set that is the middle value when the original data values are arranged in order of increasing (or decreasing) magnitude

Starting at home, emily traveled uphill to the hardware store for 606060 minutes at just 666 mph. she then traveled back home along the same path downhill at a speed of 121212 mph. what is her average speed for the entire trip from home to the hardware store and back?