Question

daca se stie 2a+3b=5 si 2c+b=7 calculati 4a+7b+2c

Answer 1

2a+3b=5 /*2  inmultim cu 2 relatia si rezulta 4a+6b=10
2c+b=7

4a+6b=10
2c+b=7       adunam cele doua relatii 
__________
4a+7b+2c=17