Quantitative Aptitude - Arithmetic Ability Questions

What is the value of [(cos 7A + cos 5A)÷(sin 7A – sin 5A)]?

The selling price of an article is 8/5th of its cost price. Then the gain percentage is

A dealer allows a discount of 15%. A customer pays an amount of Rs. 318.75 for an article. At what price is the article listed?

If 12x = 192- 112, what is the value of x?

If a - b = -1 and ab = 6, then what is the value of a3- b3?

If angles of a quadrilateral are in the ratio 3:5:9:13, find the largest angle?

P does half as much work as Q in 1/3 of the time. If together they take 15 days to complete a work, how many days will P take to do it alone?

10 identical solid spherical balls of radius 3 cm are melted to form a single sphere. In this process 20% of solid is wasted. What is the radius (in cm) of the bigger sphere?