Answer :
He made no gain
He bought 2 watches for $400
400/2=200
Each watch was $200
He gained 5% on one watch
200•1.05=210
He lost 5% on the other
200•0.95=190
210+190=400
Therefore he neither made nor lost any money
He bought 2 watches for $400
400/2=200
Each watch was $200
He gained 5% on one watch
200•1.05=210
He lost 5% on the other
200•0.95=190
210+190=400
Therefore he neither made nor lost any money