Question

(500-100)÷ y=200 какое ришение?

Answer 1

(500-100)÷y=200
400÷y=200
y=400÷200
y=2
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(500-100)÷y=200
200=200

Answer 2

500-100 / y = 200
400/y = 200
домножим 200 на y 
400/y = 200y/y
-200y + 400 / y = 0
-200y +400 = 0 :-200
y =2