$A$ discount series of $10 \%$,$20 \%$,and $40 \%$ is equal to a single discount of.......$\%$

$A$ manufacturer fixes his selling price at $33 \%$ over the cost of production. If the cost of production goes up by $12 \%$ and the manufacturer raises his selling price by $10 \%$,what is his new percentage profit?

Arun marks up the computer he is selling by $20 \%$ profit and sells them at a discount of $15 \%$. Arun's net gain percent is (in $\%$)

An $Ox$ and a carriage together cost $Rs. 8000$. The ox is sold at a profit of $10\%$ and the carriage is sold at a loss of $10\%$. If the total profit made is $2.5\%$,then what is the cost price of the ox? (in $Rs.$)

$A$ man sells an article at $5 \%$ above its cost price. If he had bought it at $5 \%$ less than what he had paid for it and sold it at $Rs. 2$ less,he would have gained $10 \%$. The cost price of the article is (in $Rs.$)

Successive discounts of $10 \%$,$12 \%$ and $15 \%$ are equivalent to a single discount of: