Răspuns:
5m stofa---------5m cat.----'''315lei/×2
10 m stofa------7 m catifea-----525lei
si-avem:
10m stofa-------10mc--------630
10mst---------------7mc----------525
--------------------------------------------'------
/-----------------------3mc= 630-525
3mc= 105, rezulta ca 1mcatifea =105÷3=35 lei apoi:
5m stofa---'--------5×35-------315
5 m stofa= 315-175,
5m stofa=140, 1mstofa=140÷5=28lei