1. $(83)_{10}$ & $(34)_{10}$

$BCD form:$

$\hspace{2.6cm} 8 \hspace{2cm} 3 \hspace{2cm} 4$

$ \hspace{2.6cm}\downarrow \hspace{2cm} \downarrow \hspace{2cm} \downarrow$

$\hspace{2.3cm}1000 \hspace{1.4cm} 0011 \hspace{1.4cm} 0100$

$83 \rightarrow \hspace{1cm} 1000 \hspace{.3cm} 0011$

$34 \rightarrow \hspace{1cm}\underline{ 0011 \hspace{.3cm} 0100}$

$\hspace{2cm} 1011 \hspace{.3cm} 0111$

$\hspace{2.3cm} \downarrow \hspace{1cm} \downarrow$

$\hspace{2.2cm} 11 \hspace{.9cm} 7$

As 11>9

11 + 6 according to the rule of BCD addition we will add '6' (0110)

$So, \hspace {2cm}1011$

$\hspace {2.64cm}\underline{0110}$

$\hspace {1.6cm}\underbrace{0001}\hspace{.2cm}\underbrace{0001}$

$\hspace {2cm}1\hspace{.8cm}1$

$(83)_{BCD} + (34)_{BCD} = (117)_{10}$

2.$(57)_{10}$ & $(26)_{10}$

57 in BCD = 0101 $\hspace{.2cm}$0111

26 in BCD = 0010 $\hspace{.2cm}$0110

$\rightarrow \hspace{1cm} 0101 \hspace{.2cm} 0111$

$\hspace{1.5cm} \underline{0010 \hspace{.2cm} 0110}$

$\hspace{1.8cm} \downarrow \hspace{.9cm} \downarrow$

$\hspace{1.8cm} 7 \hspace{.9cm} 3$

As 13>9

According to BCD addition rule, we will add '6' (0110)

$\hspace{1.7cm}0111 \hspace{.2cm}1101$

$\hspace{1.65cm}\underline{+ \hspace{.74cm}1101}$

$\hspace{1.65cm}1000 \hspace{.2cm}0011$

$\hspace{2cm} \downarrow \hspace{.8cm} \downarrow$

$\hspace{2cm} 8 \hspace{.8cm} 3$

$(57)_{10} + (26)_{10} = (83)_{10}$