$4\frac{3}{10}= \frac{4\times 10+3}{10}=\frac{43}{10}$

$21\frac{7}{100}= \frac{21\times 100+7}{100}=\frac{2107}{100}$

$7\frac{39}{100}= \frac{7\times 100+39}{100}=\frac{739}{100}$

$6\frac{123}{1000}= \frac{6\times 1000+123}{1000}=\frac{1123}{1000}$