1. Find the numbers $\overline{a b c}$ with the property that $\overline{a b c}=9 \cdot \overline{a c}$.
1. $5(a+b)=4 c$ ..... $.2 \text{p}$
$c \in\{0,5\}$ ..... $2 \text{p}$
$a+b=0 \Rightarrow a=b=0$ impossible ..... $1 \text{p}$
$\overline{a b c} \in\{405,315,225,135\}$ ..... $2 \text{p}$