Quantitative Aptitude - Arithmetic Ability Questions

Find the value of  x3 - y3, if x - y = 4 and xy = 12.

If Sumita earns 75/4% more than her boyfriend, find the approximate % her boyfriend earns less than Sunita.

In a week, how many times are the hands of a clock at right angles with each other?

What will be the sum of the measures all the interior angles of a polygon having 14 sides?

A sump is filled by three tankers with uniform flow. The first two tankers operating simultaneously fill the sump in the same time during which the sump is filled by the third tanker alone. The second tanker fills the sump 5 hours faster than the first tanker and 4 hours slower than the third tanker. The time required by the first tanker is:

One-third of Poojitha's age three years ago plus one-half of her age two years from now is twenty years. How old is she now?

Five men or ten women can complete a job in 20 days. In how many days can 3 men and 4 women complete it?

P and Q can do a project in 20 and 12 days respectively. In how many days can they complete 40% of the project if they work together?