Mobile Phone Original Price

Let the total price of the mobile phone be $X$. Amount paid via UPI and cash = $\left(\frac{1}{6} + \frac{1}{3}\right)X = \frac{1}{2}X$. Remaining balance amount = $X - \frac{1}{2}X = \frac{1}{2}X$. Interest paid = $10\%$ of balance amount = $0.10 \times \frac{1}{2}X = 0.05X$. Given $0.05X = 6000 \implies X = \frac{6000}{0.05} = 120,000$. Thus, original price is Rs. 120,000.