(1000-d×2-25×4)÷6=143
(1000-d×2-100)÷6=143 | ×6
1000-d×2-100=858 | +100
1000-d×2=958
2d=1000-958
2d=42
d=42÷2
d=21
(e-406÷2+29×4)÷3-108÷9=132
(e-406÷2+29×4)÷3-12=132 | +12
(e-406÷2+29×4)÷3=144 | ×3
e-406÷2+29×4=432
e-203+116=432 | -116
e-203=316 | +203
e=519
f÷7+25=[900-(300-48×5)×9]÷9
f÷7+25=[900-(300-240)×9]÷9
f÷7+25=(900-60×9)÷9
f÷7+25=(900-540)÷9
f÷7+25=360÷9
f÷7+25=40 | -25
f÷7=15 | ×7
f=105
