1300-(y-678)=400 Помагите

Question

1300-(y-678)=400 Помагите

Answer 1

1300-у+678=400
-у=400-1300-678
y=1578

Answer 2

1300-(y-678)=400

y-678=1300-400

y-678=900

y=900+678

у=1578

1300-(1578-678)=400