How many $kg$ of sugar costing ₹ $5.50$ per $kg$ must be mixed with $60 \ kg$ of sugar costing ₹ $4.80$ per $kg$ so that the mixture is worth ₹ $5.25$ per $kg$?

In what ratio should two varieties of tea,one costing ₹$25$ per $kg$ and the other costing ₹$30$ per $kg$,be blended to produce a blended variety of tea worth ₹$28$ per $kg$?

$A$ person has a chemical costing $Rs. 25$ per $litre$. In what ratio should water be mixed in the chemical so that by selling the mixture at $Rs. 20$ per $litre$,he may get a profit of $25\%$?

$A$ person has $60$ pens. He sells some of these at a profit of $12 \%$ and the rest at $8 \%$ loss. On the whole,he gets a profit of $11 \%$. How many pens were sold at $12 \%$ profit and how many at $8 \%$ loss?

Solution $A$ contains $10 \%$ acid and solution $B$ contains $30 \%$ acid. In what ratio should solution $A$ be mixed with solution $B$ to obtain a mixture with $25 \%$ acid?

Some amount out of ₹$7000$ was lent at $6 \%$ $p.a.$ and the remaining at $4 \%$ $p.a.$ If the total simple interest from both the fractions in $5$ $years$ was ₹$1600$,the sum lent at $6 \%$ $p.a.$ was (in ₹).