\(53\cdot39-47\cdot39+53\cdot21+47\cdot21\)
\(=39\cdot\left(53-47\right)+21\cdot\left(53+47\right)\)
\(=39\cdot6+21\cdot100\)
\(=234+2100\)
\(=2334\)
53 x 39 - 47 x 39 + 53 x 21 + 47 x 21
= (53 - 47) x 39 + ( 53 + 47) x 21
= 6 x 39 + 100 x 21
= 234 + 2100
= 2334