after allowing 20%discount on the m. p of a mobile,15% vat was levied and sold it. If the differences between selling price with vat and selling price after discount is rs.1800,find the marked price of the mobile

Market price = Rs. 15,000

Step-by-step explanation:

Let Market price = x

discount = 20% of x

              = 0.20 *x = 0.2x

Selling price after discount = x - 0.2x = 0.8x

Value added tax = 15% of 0.8x

                            = 0.15 * 0.8x

                           = 0.12x

Selling price with VAT = 0.8x + 0.12x = 0.92x

Differences between SP with vat and SP after discount = rs.1800

0.92x - 0.8x = 1800

0.12 x = 1800

x = 1800/0.12

x = Rs. 15,000

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50