Question

determinati numerele a si b stiind ca suma lor este 431 iar 2a+5b=1696

Answer 1

a+b=431
2a+5b=1696
a=431-b
2(431-b)+5b=1696
862-2b+5b=1696
3b=1696-862
3b=834
b=834:3
b=278
a=431-b
a=431-278
a=153

Answer 2

a+b=431 deci b=431-a
 si-l inlocuim in ecuatia a 2-a. 
Avem

2a+5(431-a)=2a+2155-5a=-3a+2155=1696 de unde a=(2155-1696):(-3)=
=-459/3= -153
si rezulta
b=431-a=431-(-153)=431+153= 584

Succes!