How much percent more than the C.P. should a manufacture mark his goods so that after allowing a discount of `20%` on the marked price he gains `10%` /

Explanation

Let the CP=Rs `100`
Gain percent required = `10%`
S.P = `Rs(100+10) = Rs 110`
Discount allowed = `20%`
Let the MP be `x`
Discount=`20%` of `x`
`=>(20/100 xx x)=Rs x/5`
SP=MP-Discount
=Rs`(x-x/5)=Rs (4x)/5`
But SP=Rs 110
`therefore (4x)/5=110`
x=`550/4`
`x=Rs 137.50`
`MP=137.50`
Hence, the required increase=`137.50-100=37.50%`