Albert buys $4$ $horses$ and $9$ cows for $Rs. 13400$. If he sells the horse at $10 \%$ profit and the cows at $20 \%$ profit, then he earns a total profit of $Rs.\, 1880 .$ The cost of a horse is (in $Rs.$)

The cash difference between the selling price of an article at a profit of $4 \%$ and $6 \%$ is $Rs.$ $3 .$ The ratio of the $2$ selling price is?

Mohit purchased $40\, kg$ of wheat at $Rs.\,12 .50$ per $kg$ and $25\, kg$ of wheat at $Rs.\,15.10$ per $kg.$ He mixed the two qualities of wheat for selling. At what rate should it be sold to gain $10 \% ?$ (in $Rs.)$

A man purchased $150$ pens at the rate of $Rs.\, 12$ per pen. He sold 50 pens at gain of $10 \% .$ The percentage gain at which he must sell the remaining pens so as to gain $15 \%$ on the whole outlay is........$\%$

A man bought apples at the rate of 6 for $Rs.\,20$ and sold them at $4$ for $Rs.\, 16.$ His estimated profit $\%$ is

A tradesman gives $4 \%$ discount on the marked price and gives $1$ book free for buying every $15$ books and thus gains $35 \% .$ The marked price is increased above the cost price by (appx.) (in $\%$)