Question

Daca 2a+b=22 si a+b=12, calculeaza 3a+2b.

Answer 1

2a+b=22
a+b=12
2a +a=3a
b+b=2b
3a+2b=22+12
3a+2b=34

Answer 2

$2a+b=22 \Rightarrow b=22-2a \\ a+b=12 \Rightarrow a+22-2a=12 \Rightarrow a-2a=12-22 \Leftrightarrow \\ \Leftrightarrow -a=-10 \Rightarrow \boxed{a=10} \\ b=22-2a \Rightarrow b=22-2 \cdot 10 \Rightarrow b=22-20 \Rightarrow \boxed{b=2} \\ 3a+2b=3 \cdot 10+2 \cdot 2=30+4=34 \\ \boxed{3a+2b=34}$