How do you get from 6:7 to 39?

Question

The school drama club sponsored a guessing game at a fair.They put some blue marbles and some green marbles in a box.People had to guess how many of each were in the box given two clues.

1.There were 52 marbles in total in the box.

2 The ratio of blue marbles to green marbles was 8:5.

 

Answer 1

Let x = number of blue marbles 

 

Then, 52-x = number of green marbles

 

Since the ratio of blue to green is 8:5, we can say that 8/5 = x/(52-x)

 

Cross multiply to get 8(52-x) = 5x

 

416 - 8x = 5x

 

      416 = 13x

 

         x = 32

 

There are 32 blue marbles and 20 green marbles.

 

 

Answer 2

there are 52 marbles

the ratio of blue to green is 8:5

8+5=13

52/13=4

4*8=32 blue marbles

4*5=20 green marbles

blue     green

8         5     13 no

16       10   26 no

24       15   39 no

32       20   52 yes