4800 : ( X x 16 ) = 25
X x 16 = 4800 : 25
X x 16 = 192
X = 192 : 16
X = 12
2009 : ( 71 : x ) = 2009
71 : x = 2009 : 2009
71 : x = 1
x = 71 : 1
x = 71
4800 : ( x . 16 ) = 25
x . 16 = 4800 : 25
x . 16 = 192
x = 192 : 16
x = 12
4800 : ( X x 16 ) = 25
X x 16 = 4800 : 25
X x 16 = 192
X = 192 : 16
X = 12