The answer is that: there is 62% of 310? The answer is 186 pages.
Ratio:
Red : Total
2 : 5
(x2) (x2)
4 : 10
Green : Total
3 : 10
Total of red and green marbles = 4 + 3 = 7
Blue marbles = 10 - 7 = 3
10 parts = 40 marbles
1 part = 40 ÷ 10 = 4
3 parts = 4 x 3 = 12
Answer: There are 12 blue marbles.
If you are working out the number of KM per CM them you divide the KM by the CM:
15/0.75 = 20
This means that it is 20KM per every 1CM
Hope this helps! :)