What is the least 1/2 x 3/4, 3/4 + 1/8, 1/2 + 1/4

What is the value of x in the following equation. -x ^3/2 = -27

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

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?