Please see: Make the largest box from a cardboard sheet
Thanks to his older brother's friends: @Oray, @Weather Vane and @mlk, the boy managed to make as large cardboard box as possible. Unfortunately, it was not enough to store all his toys responsible for causing mess in his room.
To do something about it, he asked his parents for another sheet to make another box. Unfortunately his father just cut off a (little bit larger) piece from remaining sheet already and used it to temporarily patch a hole in his greenhouse, so only
60cm x 39cm piece still remains.
Now the problem is similar, what is the largest box the boy can make using
60cm x 39cm cardboard piece?
Rules are the same as previously.