Question

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41,42,43,44,45,46,47.48
la 45 cerintele sunt:
a)Ce procent din suma a cheltuit prima data?
b)Ce suma a avut initial?

Answer 1

41)X suma de bani depusa
15 X %=15X/100=(se simplifica)cu 5=3X /20
peste doi ani
115X/100 ori 16/100=23X/125
23X/125 -3X/20=13,6
aducem la acelasi numitor 500
92X-75X=6.800
17X=6800
X=6.800/17
X=4.000 lei
42)
40 leix25%=10 lei
40 lei+10 lei=50 lei
40 lei * X/100=50 lei
40X/100=50 lei
40X=5000 lei
X=5000 lei/40
X=20%
43)x+y+z=3000 pagini
x-75/100 *x=y-80/100*y=z -2/3*z
x-3x/4=y-4y/5=z-2z/3 aducem la acelasi numitor 60 si
60x-45x=60y-48y=60z-40z
15x=12y=20z
15x=12y
x=12y/15=>
x=4y/5
20z=12y
z=12y/20=
.z=3y/5
inlocuim in x+y+z=3000
4y/5+y+3y/5=3000
aducem la acelasi numitor
(4y+5y+3y)/5=3000
12y=3000 *5
12y=15.000
y=15.000/12
y=1250pagini
x=4*1250/5=>
x=4*250=>x=1000 pagini
z=3*250=>z=750 pagini
x=primul volum=1000pagini
y=al doilea volum=1250 pagini
z=al treilea volum=750 pagini

44) a)x-pretul initial
x-15/100*x=x-15x/100=85x/100=17x/20
17x/20=y
y=5,75lei-1,15lei
y=4,6lei
17x/20=46/10
17x/20=92/20
17x=92
x=92/17
x=6 lei
b)6lei*15%=6*15/100=0,9lei
6,9lei
1,15lei/6,9lei=16,67%
45a)x-x/4=25 %
b)x=suma de bani
 X -X/4-X/4/2=7,5 lei
x-x/4=3x/4
x-3x/4/2=x - 3x/8=8x-3x/8=5x/8
5x/8=7,5 lei
5x=7,5lei*8
5x=60 lei
x=60lei/5
x=12lei
46)
a)30elevix30%=9 elevi au 10 la fizica,
   matematica 30x50%=15 elevi
 chimie  30x40%=12elevi
b) 9%din 15=9*15/100=135/100=1,35%
c)9elevi+15elevi+12elevi) -X=30 elevi
36 elevi-x elevi=30 elevi
x=6 elevi
47) a) x pretul initial
x-8/100*x=322 lei
     x-8x/100=322 lei
     100x-8x/100=322 lei
     92x=32200lei
x=32200/92
x=350 lei
b)mai putin de 300 lei este 299 lei
350 lei - p/100*350=299 lei
350 lei-350p/100=299lei
350 lei-35p/10=299lei
3500lei-35p=2990 lei
-35p=2990lei-3500lei
35p=501
p=501/35
p=14,31=>p=15
p=15
48)
A)A)7500E +40/100*7500E= 7500e+3000e=10500 e
10.500*24/100=2.520 Euro TVA-ul
B)10500E+2520E=13.020 Euro
c)
13.020*20/100=2.604 Euro(avansul)
13.020 - 2.604=10.416 Euro
10.416 Euro /24 rate= 434 euro pe luna