A dealer sells two machines at the rate of Rs. 15000 per machine. On one he earns a profit of 20 percent and on the other he loses 40 percent. What is his profit/loss percentage in the whole transaction ?

20 percent loss

Loss % = 40% =  \(\frac{2}{5}\)

Profit % = 20% =  \(\frac{1}{5}\)

           CP            SP

1st      5               6

2nd     5               3

Given SP is equal so make SP equal

           CP              SP

1st      5               6 

2nd    ( 5             3)× 2

           CP              SP

1st        5               6

2nd      10              6

     ————————————

           15             12

Loss = 15 - 12 = 3

Loss% =  \(\frac{3 × 100}{15}\)= 20%