Răspuns:
12. a+b= 125000 lei
a-10%a= b+b%10
a- [tex]\frac{a}{10}[/tex]= b+ [tex]\frac{b}{10}[/tex] aducem la acelasi numitor
10a-a= 10b+b 9a=11b a=11b/9
11b/9+b=125000 aducem la acelasi numitor
11b+9b= 125000*9 20b= 125000*9
b= 125000/20 *9= 56250 b= 56250 lei
a= 11*56250/9= 6250*11= 68750 a= 68750 lei
15. a+b= 35 apart 2a+3b=85 camere
pp ca toate apart au 3 camere
3*35= 105 camere ( ar fi fost)
105-85 = 20 camere
3-2=1 camera diferenta
20:1 = 20 apart cu 2 camere
20*2=40 camere 85-40=45 camere
45:3= 15 apartamente cu 3 camere
