Question

Replace A, B, C by suitable numerals:
$$\begin{gathered} \begin{array}{cccc}& 5& 7& A\\ -& C& B& 8\end{array} \\ \overline{\underline{\begin{array}{cccc}& 2& 9& 3\end{array}}} \end{gathered}$$

Answer 1

$A-8=3$
​This implies that 1 is borrowed.
$$\begin{gathered} 11-8=3 \\ \Rightarrow A=1 \end{gathered}$$

Then, $7-B=9$
1 is borrowed from 7.
∴ $$\begin{gathered} 16-B=9 \\ \Rightarrow B=7 \end{gathered}$$

Further, $5-C=2$
But 1 has been borrowed from 5.
∴ 4 - C = 2
$\Rightarrow C=2$

∴ $A=1,B=7andC=2$