Answer:
x = 26.244
Explanation:
Let the angle opposite the side of length 15 be A and the angle opposite the side with length 18 be B
if a is the side with length 18 and b is the side with length 15
then the relationship between the two know sides a and b and the included angle C is given by the law of cosines



cos(105) = -0.2588






Since x cannot be negative,
x = 26.244 Answer