1.
x=suma
x/4=ziua 1
2x/5=ziua 2
x/6=ziua 3
x/4+2x/5+x/6+77=x
15x+24x+10x+4620=60x
11x=4620
x=420 lei
2.1 robinet umple bazinul in 20 min
al 2-lea robinet umple bazinul in 30 min
amandoua robinetele ar umple 2 bazine in 30+20=50 min
deci amandoua robinetele ar umple un bazin in 50:2=25 min
4 min.........200 l
25 min..........x l
25x200/4=1250 l capacitatea bazinului
3.100%-15%=85%
1377:85%=1620 lei
100%-10%=90%
1620:90%=1800 lei pret initial
4
x=numarul
x/4+x/3+12=x-3
3x+4x+144=12x-36
5x=180
x=36