In a bag, the ratio of red to blue counters is 3:4.
If 3 red counters are removed the ratio of red to blue counters becomes 3:5.
How many blue counters are there in the bag?

Respuesta :

r/b = 2/3, so r = 2/3 b
(r-3)/b = 3/5
5(r-3) = 3b
5(2/3 b - 3) = 3b
Just solve for b