Find the length of X

The height of a triangle is 4 in. greater than twice its base. the area of the triangle is no more than 168 in.^2. which inequalitycan be used to find the possible lengths, x, of the base of the triangle?

The length of the line segment joining the midpoints of sides ab and bc of the parallelogram abcd is 10. find the length of diagnol ac

What is the interquartile range of this data set? 2, 5, 9, 11, 18, 30, 42, 48, 55, 73, 81