Răspuns :
(36-20:a×9)=0....
36-20:a×9=0....
20:a×9=36....
20:a=36:9...
20:a=4...
a=20:4 ...
a=5
obligatoriu 36 - 20 : a x 9 = 0
20 : a x 9 = 36
20 : a = 36 : 9
20 : a = 4
a = 20 : 4
a = 5
20 : a x 9 = 36
20 : a = 36 : 9
20 : a = 4
a = 20 : 4
a = 5