## Task 34/80

Determine $s_{40}$ of an arithmetic series of 1st order with:

1. $a_{1}=10 a+b=x$ with $a ; b \in N ; 1 \leq a \leq 9 ; 0 \leq b \leq 9$,
2. $a_{40}=10 c+d=y$ with $c ; d \in N ; 0 \leq c ; d \leq 9$,
3. $s_{40}=\sum_{i=1}^{40} a_{i}=1000 a+100 b+10 c+d$