Question

75 + а = 800 - 700
с - 40 = 100 - 80

Answer 1

75 + а = 800 - 700
75 + а = 100
а = 100-75
а=25
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75+25=800-700
100=100

с-40=100-80
с-40=20
с=20+40
с=60
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60-40=100-80
20=20