Question

7a+3b=85

a=2b
nu stiu sa o rezolv
AJUTOR dau coronita

Answer 1

7a+3b=85
a=2b
7x2b+3b=85
14b+3b=85
17b=85
b=5
a=2*5=10

Answer 2

$\displaystyle 7a+3b=85 \\ a=2b \\ 7a+3b=85 \Rightarrow 7 \cdot 2b+3b=85 \Rightarrow 14b+3b=85 \Rightarrow 17b=85 \Rightarrow \\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ \Rightarrow b= \frac{85}{17} \Rightarrow \boxed{b=5} \\ a=2b \Rightarrow a=2 \cdot 5 \Rightarrow \boxed{a=10}$