Let the marked price = Rs.x

The discount equivalent to successive

discounts 20% and 10% =\( \Large  \left(r_{1}+r_{2}-\frac{r_{1}r_{2}}{100}\right) \)%

where, \( \Large r_{1} \) = 20 and \( \Large r_{2} \) = 10

Then, 30 - 2 = 28%

According to the question,

\( \Large \frac{ \left(100-28\right)x }{100}-\frac{ \left(100-30\right)x }{100} = 72 \)

\( \Large \frac{72x - 70x}{100} = 72 \)

\( \Large \frac{72 \times 100}{2} \)=Rs.3600