In triangle ABC, a line is drawn from the vertex A to a point D on BC. If BC = 9 cm and DC = 3 cm, then what is the ratio of the areas of triangle ABD and triangle ADC respectively?
If a young son works quickly for 2 hours and prepares 16 items in a day, and his old father works slowly for 8 hours and prepares 24 items in a day, which of the following is true?