Question

1) Alexandra si Costin au impreuna 110.000 lei.Dca Costin i.ar da Alexandrei 30.000 lei, acesta ar vea mai mult decat el cu 30.000 lei.Cati lei are fiecare?

2) Suma a doua numere naturalr este 32. Calculati cate solutii are problema daca fiecare dintre numere este mai mare ca 11..

Answer 1

a=suma alexandra
b=suma costin
a+b=110000
a+30000-30000=b-30000
a=b-30000
b-30000+b=110000
2b=140000
b=70000
a=140000-70000=70000

2.
a+b=32
a>11
b>11

a={12,13,14,15,16,17,18,19,20}
b={20,19,18,17,16,15,14,13,12}
avem 9 solutii

Answer 2

1. a+c=110000[lei];
⇒c-30000=a+30000;
⇒c=30000+a+30000;
⇒c=60000+a;
⇒a+a+60000=110000
⇒2a=50000⇒a=25000[lei-Alexandra];
⇒c=60000+25000
⇒c=85000[lei-Costin];
2. a+b=32;
⇒a>11⇒b>11;
⇒a,b∈[[12,20],[13,19],[14,18],[15,17],[16,16],[17,15],[18,14],[19,13],[20,12]⇒4·2+1=8+1=9⇒solutii are problema;