Question

Postcards costing 30 paise each and inland letters costing rs 1.50 each were purchased for rs. 66. Total number of postcards and inland letters purchased was 60. If the number of postcards and inland letters is interchanged, then the cost is:

Answer 1

Answer:

Rs 42

Step-by-step explanation:

Let there be x postcards and y inlands.

        x + y = 60

    30x + 150y = 6600

Solving these equations,

       30x + 30y = 1800

 (-)   30x + 150y = 6600

              -120y = 4800

                     y = 40

                     x = 20

On interchanging inland and postcard,

                     x = 40 and y= 20

                      = 40 x 0.3 + 20 x 1.5

                      = Rs 42