$\displaystyle {n}$ psychology students took a standardized test. The scores are summarized in the GFDT below.

Scores	Frequency
40 - 44	13
45 - 49	15
50 - 54	18
55 - 59
60 - 64	13
65 - 69	50

The scores are also described in the cumulative table shown below.

Scores	Frequency
less than 45	13
less than 50	28
less than 55	46
less than 60	57
less than 65	70
less than 70	$\displaystyle {n}$

What is the missing value in the GFDT?

answer =