3A+AB=B0 B=?

\(\text{Do you actually mean }(30 + A) + (10A + B)= 10B\;\text{?}\)

If so we will have to try each positive 1-digit integers.

 

First substitute A = 1

31 + 1B = B0

B have to be 9 so A = 1 didn't work.

 

Substitute A = 2

32 + 2B = B0

B have to be 8, so A = 2 didn't work.

 

Substitute A = 3

33 + 3B = B0

B have to be 7. We did it.

33 + 37 = 70.

 

B = 7

A(3+B)= B0

3+B= B0/A

B= (B0/A) - 3