[560:(78-c)+790]:7=6x5x4-6
[560:(78-c)+790]:7=30x4-6
[560:(78-c)+790]:7=120-6
[560:(78-c)+790]:7=114
560:(78-c)+790=114x7
560:(78-c)+790=798
560:(78-c)=798-790
560:(78-c)=8
78-c=560:8
78-c=70
c=78-70
c=8
(dx2-190):6+3x295=1000
(dx2-190):6+885=1000
(dx2-190):6=1000-885
(dx2-190):6=115
dx2-190=115x6
dx2-190=690
dx2=690+190
dx2=880
d=880:2
d=440