1) When you're finding ratios, the best thing to do is to add the parts together to find what one part is.
2+4= 6. Then divide this by the total- 18/6=3.
Therefore, the ratio of red to brown chairs is 2*3:4*3
Therefore, the amount of red chairs is 12.
2) The best thing to do i to find out how long it takes him to read one book them multiply this by 15.
To do this, simply divide the amount of time by the amount of books that he has read.
30/10= 3
Therefore, Rock can read a book in three minutes. As he is reading 15, you multiply these together.
3*15= 45
Therefore, it will take Rock 45 minutes to read 15 books.
3) The best thing to do is to find out what one pastry costs, and you can do this by dividing the cost by the amount of pastries.
160/8= 20.
Therefore, one pastry costs $20.
As you want to find the cost of 16 pastries, you simply times these together.
20*16= 320
Therefore, 16 pastries cost $320.
Hope this helps :)
