If a : b = 20:5 then find out the value of (13a-9b): (11a-7b)?

What must be added to two numbers that are in the ratio of 3:4, so that they become in the ratio 4:5?

Rs. 425 is divided among 4 men, 5 women and 6 boys such that the share of a man , a woman and a boy may be ratio of 9:8:4. What is the share of a woman?

Find the forth proportional to $${ x^{2}b^{2}c^{3}}$$, $${ x^{3}bc^{4}}$$ and $${ x^{4}b^{2}c^{2}}$$.

Two numbers are in the ratio of 3: 5. If 9 be subtracted from each, then they are in the ratio of 12: 23. Find the numbers. 

In a factory men, women and children were employed in the ratio 8:5:1 to finish a job and their individual wages were in the ratio 5:2:3. Total daily wages of all amount to Rs. 318. Find the total daily wages paid to each category.

The third proportional of two numbers 4 and 20 is

There are three bottles of mixture of syrup and water of ratio 2 : 3,  3 : 4,  7 : 5. 10 Litres of first and 21 Litres of second bottles are taken. How much quantity from third bottles is to be taken so that final mixture from three bottles will be of ratios 1 : 1.