question from IQ test

[francois.cheynier]

I found this sentance in a web site but I don't understand it. Can you please help me to translate it ?

"If you buy 3 trousers worth 23€30 each with a 50€ note, how much change are you left with?"

It's in an IQ test and the answer is : 13,1€

thanks a lot

[Thomas]

Welcome to the forum, francois.cheynier!

It would translate to

"Si vous achetez 3 pantalons à 23€30 chacun avec un billet de 50€, combien de monnaie vous reste?"

Or that in better French...

However...I have NO idea where the 13,1€ comes from...the way I see it:

3 trousers x 23€30 = 69€90

So...you still have to pay 19€90? Or if you use three 50€ notes, you pay 150€ and get 80€10 in change...but I have no idea where the 13,1€ comes from! Perhaps the questions is typed incorrectly?