5x11/5= 9x7/...=7 7/3x3= 3x.../3=12

n*a/n = a

1) 5=> n
11 => a
Donc 5*11/5 = 11

2) 9=>n
7 => a
Donc 9*7/9 =7

3) 3 => n
7=> a
Donc 7/3*3 = 7

4) 3=> n
12=> a
Donc 3*12/3=12