10. 4:5....added = 9
4/9 (1800) = 7200/9 = 800 (red)
5/9 (1800) = 9000/9 = 1000 (green)
there were (1000 - 800) = 200 less red ones then green ones.
11. 7/4 = 21/r
cross multiply
(7)(r) = (4)(21)
7r = 84
r = 84/7
r = 12....Rod has 12 stickers
12. 14/4 = 3.5 eggs per cup
for 16 cups...16 * 3.5 = 56 eggs