Răspuns:
x= cantitatea initiala de lichid
x·1/4=x/4 L - s-au scos in prima zi
x-x/4=4x/4-x/4=3x/4 - rest1
3x/4·2/9+10=x/6+10=(x+60)/6 L - s-au scos a2a oara
3x/4-(x+60)/6=9x/12-2(x+60)/12=(9x-2x-120)/12=(7x-120)/12 - rest2
(7x-120)/12·1/3=(7x-120)/36 L - s-au scos a3a zi
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x/4+(x+60)/6+(7x-120)/36+40=x aducem la acelasi numitor
9x+6x+360+7x-120+1440=36x
1680=36x-22x
x=1680:14
x=120 L erau initial in vas
________
V: 120-120:4-(120+60):6-(7·120-120):36=120-30-180:6-720:36=
=120-30-30-20=40 L rest