If two mixers and one T.V. cost Rs. 700. While two T.V.s and one mixer cost Rs. 980. The value of one T.V. is :

Rs.420

Let the cost of one mixer = Rs.x 

and the cost of one T.V. = Rs.y

Then, according to the question

            2x + y   = 700  ..........(i)

              x + 2y = 980 ...........(ii)

Solving the eq. (i), (ii) 

Multiply eq. (ii) by 2 

            2x + y   = 700

            2x + 4y = 1960

           -     -        -       

        ________________

                    3y = 1260 or y = 420

The cost of one T.V. = Rs. 420