A lending library has a fixed charge for the first 40days and an additional charge for each day thereafter. Brian paid €61 for a book he kept for 90days while Elli paid €31 for the book she kept for 60days. Find the fixed charge and the charge for each extra day.
A wooden toy rocket is in the shape of a cone mounted on a cylinder as shown in the figure. The height of the entire rocket is 37cm, while the height of the conical part is 29cm. The base of the conical portion has a diameter of 16cm, which the base diameter of the cylindrical portion is 11cm. If the conical portion is painted orange, find the area of the rocket painted with orange colours.
A box contains 6 yellow and 7 green balls. Anton takes out a ball, puts it back, and then takes out another ball. What is the probability that both balls were yellow?