38.
a)100%-8%=92%
322:92%=350 lei pret initial
b) 350-300=50
50:350=0,1428 =14,28% alegem 15%
350x15%=52,5 lei
350-52,5=297,5 lei
39.
a=nr pag vol.1
b=nr pag vol.2
c=nr pag vol.3
a+b+c=3000
a-75%a=b-80%b=c-2c/3
25%a=20%b=c/3
a/4=b/5=c/3
c=3a/4
b=5a/4
a+5a/4+3a/4=3000
4a+5a+3a=12000
12a=12000
a=1000 pag
b=5*1000/4=1250 pag
c=3*1000/4=750 pag
b) x=750/1250=0,6=60%
40.
7500 x 40%=3000 euro
7500+3000=10500euro
a)10500x24%=2520 euro
b)10500+2520=13020euro cu TVA
13020x20%=2604 euro
13020-2604=10416 euro
c)10416:24 rate=434 euro/luna
41.
240 g 15 % concentratie
a)
15g...........100 g solutie
x............240
x=240*15/100=36 g
b) 10g.......100 g solutie
36g........x
x=36*100/10=360 g solutie
360-240=120 g de apa trebuie adaugata
