Question

Find $A$ in the addition
$17A$
$\underset{–}{+2A4}$
$\underset{–}{407}$

Answer 1

Here at unit place:

$A+4=7⟹A=3$

At tens place:

$7+A=0$ here we must have a $10$ to ensure zero result: So $A+3$

Hence $A=3$