Question

if the CP of 6 pen is equal to the sp of 4 pen find the gain

Answer 1

we know we will need gain amount to get gain percent, right. So lets get gain first. Let the cost price of 1 pen is Re 1 Cost of 4 pens = Rs 4 Selling price of 4 pens = 6 Gain = 6- 4 = 2 Gain%=(Gain/Cost∗100)%=(2/4)%=50%

Answer 2

CP of 6 pens= x
therefore, CP of 1 pen = x/6

SP of 4 pens = CP of 6 pens= x
therefore, SP of 1 pen = x/4

therefore, gain = (1/4-1/6)x                     [L.C.M = 12]
= [(3-2)12]x
= 1/12 x

gain percent = (gain / CP)*100
= [(x/12)/(x/6)]*100
= (x/12)*(6/x)*100             [ both the x gets cancelled ]
= (1/2)*100
= 50 %

Answer : gain made by selling 1 pen =  50 %