Đáp án:
$b) VT= \frac{\overline{a00a}}{\overline{b00b}}=\frac{1000a+a}{1000b+b}=\frac{1001a}{1001b}=\frac{a}{b}=VP\\
c) VT=\frac{\overline{ab00ab}}{\overline{cd00cd}}=\frac{100000a+10000b+10a+b}{100000c+10000d+10c+d}\\
=\frac{100010a+10001b}{100010c+10001d}=\frac{10001(10a+b)}{10001(10c+d)}\\
=\frac{(10a+b)}{(10c+d)}=\frac{\overline{ab}}{\overline{cd}}$