Question

Daca x+3y=49 si x+5y=81 determinati x+4y

Answer 1

din prima ecuatie avem       x=49-3y si o inlocuim in a doua 49-3y+5y=81
49+2y=81
2y=32,
y=16

x= 49-3*16
x=49-48
x=1

x+4y= x+2*2y= 1+2*32=65