(x-300)+800=1400
x-300+800=1400
x+500=1400
x=1400-500
x=900
6400-(1700+y)=2500
6400-1700-y=2500
4700-y=2500
-y=2500-4700
-y=-2200
y=2200
(w+7250)-3250=20870
w+7250-3250=20870
w+4000=20870
w=20870-4000
w=16870
25620+(13200-z)=30000
25620+13200-z=30000
38820-z=30000
-z=30000-38820
-z=-8820
z=8820
(x-300)+800=1400
x-300+800=1400
x+500=1400
x=1400-500
x=900
6400-(1700+y)=2500
6400-1700-y=2500
4700-y=2500
-y=2500-4700
-y=-2200
y=2200
(w+7250)-3250=20870
w+7250-3250=20870
w+4000=20870
w=20870-4000
w=16870
25620+(13200-z)=30000
25620+13200-z=30000
38820-z=30000
-z=30000-38820
-z=-8820
z=8820