(3-3)*3+3/3=1
(3+3)*3-3*3=9
(3-3)3+3+3= 6
и т.д
6*900-4*900=5400-3600=1800
10*700-8*700= 7000-5600=1400
17*800-10*800=13600-8000=5600
11*900-8*900=9900-7200=2700
12*400-6*400=4800-2400=2400
21*60-10*60=1260-600=660
2,2-1,5х+9=-2,4-3,2х
-1,5х+3,2х=-2,2-2,4-9
1,7х=-13,6
х=-13,6:1,7
х=-8
Ответ: -8