Question

ofer 43 de puncte!!!! va rog problemele 36,37,38,39

Answer 1

 36) x/4+2x/5+x/6+77=x

30x+48x+20x+4620=120x

98x+4620=120x

4620=120x-98x

X=4620:22

X=420 lei

37)in cat timp umplu bazinul ambele robinete deschise concomitent? 

  (20 + 30) : 2= 50 : 2 = 25 minute

acum aplicam regula de trei simpla

daca in 4 minute ---se umplu------------200 l
          in 25 min.........se umplu      .......x  l

x =  (25 x 200) : 4 = 5000 : 4 = 1250 l

Deci bazinul are o capacitate de 1250 l

38) 100%-15% = 85%

1377:85% =1620

100%-10% = 90%

1620:90% = 1800 lei pretul initial

39)

x/4+x/3+12=x-3

x/4+x/3-x=-3-12

3x+4x-12x=-3-12

7x-12x=-15

-5x=-15

x=3