This is similar triangles where the large one is proportional to the smaller triangle inscribed inside it. Lay the 2 triangles out like so and the 30(hypotenuse) is proportional to 18. You can use the scale factor to find the "x" by doing: 24/1.66666666667(which is the scale factor you get from 30/18). This should give you 14.4.
Let the number of years after 2001 be x, then 1280000 + 19500x = 1700000 19500x = 1700000 - 1280000 = 420,000 x = 420000/19500 = 22 years. x = 22 years.
You add the total number of balls, which is 10. and then it is asking for brown balls and looking at the equation you know there are 3. so 3/10 is .30 which is 30%
