Percent problems and financial mathematics

The number \(\frac{1} {2} + \frac{1} {3}\) is bigger than \(\frac{1} {2} -\frac{1} {3}\). Express the difference between these numbers in percents of the smaller quantity.

The pad in the form of (not necessarily regular) octagon is manufactured from a square. The side of the square is \(4\, \mathrm{cm}\). An isosceles right triangle of the hypotenuse \(1\, \mathrm{cm}\) is removed from each corner of the square which results in the desired octagon. How much of the material of the initial square goes to the waste?

If a number \( 3b \) is by \( 20\% \) bigger than half of the number \( 2a + b \), then the number \( a \) is bigger than \( b \) by

One half of a number \( a \) is by \( 25\% \) smaller than one third of a number \( b \). Then the number \( b \) is