Answer to Problem # 23:

    ½   x   90 ft.   x   20 sec.   x   20 sec.  x   min. 
           min x sec.                                         60 sec.

     ½   x   90 ft.   x   20  x   1/3   =   10   x   30 ft.  =

                               300 ft. (ANSWER) 
 

 
return