2/21 * 7/8
14/168
divide top and bottom by 14
1/12
4 cups = 18 g
Divide all by 4 to get 1 cup.
1 cup = 18/4
1 cup = 4.5g
7/21 or 1/3rd, it's just a ratio of white to all, there's 7 white straws and 21 in all, then you can simplify it down to 1/3rd.
X| 1 | 15 | 225 |
y| 4 | ? | 900 |

therefore
[tex]\dfrac{4}{1}=4;\ \dfrac{900}{225}=4;\ \dfrac{?}{15}=4\to?=60[\tex]
Answer: ? = 60