х * 9 = 720
х = 720 : 9
х = 8
х + 9 = 720
х = 720 - 9
х = 711
300 : х = 60
х = 300 : 60
х = 5
300 - х = 60
х = 300 - 60
х = 240
х : 90 = 9
х = 9 * 90
х = 810
х - 90 = 9
х = 9 + 90
х = 99
1) 9x=720
x=720:9
x=80
2)x+9=720
x=720-9
x=711
3) 300:x=60
x=300:60
x=5
4) 300-x=60
x=300-60
x=240
5)x:90=9
x=90*9
x=810
6)x-90=9
x=90+9
x=99
