The total length of a line segment is the sum of the lengths of its parts.
MQ = MK + KQ . . . . . . express the relationship between the segments
15 in = 7 in + KQ . . . . . fill in the given information
(15 - 7) in = KQ . . . . . . .subtract 7 in
KQ = 8 in . . . . . . . . . . . simplify
The measurement of KQ is 8 inches.