Firstly let us solve for unit’* place,
7 + B = A
And for ten’* place,
3 + A = 9
Which means that A = 6 and B = -1 which is not possible.
So, there should be one carry in ten’* place which means 7 + B >9
3 +A +1 = 9
A = 9-1-3
= 5
For unit’ place subtracting 10 as one carry is given to ten’ place,
7 + B – 10
= 5
B = 5+10-7
= 8
∴A = 5 and B = 8
