If I did it right then x would equal 3.
18 m min 100 cm 30 cm
------ x ----- x --------- = ------
min 60 s m s
-Average acceleration is (v2-v1)/(t2-t1). And we are told that he has constant acceleration of 1.5. Since acceleration is constant, constant=average. So:
a=(v2-v1)/(t2-t1) which in this case is:
(9-2)/t=1.5
7=1.5t
t=14/3 seconds
t= 4 2/3 seconds
Cross multiply or just multiply both sides by 24
24x/6=36
4x=36
divide both sides by 4
x=9