Question

$\begin{array}{cc}BA& \\ -AB& \\ 1B& \end{array}$
A =_____ and B =_____

• A. A = 6, B = 3
• B. A = 6, B = 8
• C. A = 8, B = 6
• D. A = 4, B = 8

Answer 1

The correct option is B A = 6, B = 8

Since result is positive; BA > AB or B > A.
If B > A, to subtract B from A; we will have to borrow '1' from B.

BA (B-1) 1A
- AB - A B
_____ _________
1 B 1 B

∴ Now, we have

1A - B = B

10 + A - B = B

10 + A = 2B ____(1)

In second column, we have

B - 1 - A = 1

or B - A = 2 ____(2)

From equation (2), we get the possible values as shown below

$$\begin{array}{cc}\text{A}& \text{B}\\ \text{0}& 2\\ \text{1}& 3\\ \text{2}& 4\\ \text{3}& 5\\ \text{4}& 6\\ \text{5}& 7\\ \text{6}& 8\\ \text{7}& 9\end{array}$$

The set of values that satisfies equation (1) are A = 6 and B = 8.
So, A = 6 and B = 8.