Question

Audrey has some guppies in a fish tank. The ratio of the orange guppies to silver guppies is 3:5. She has 12y orange guppies. Write the number of silver guppies she has in terms of y.

Answer 1

By proportion:-

3/5  =  12y / xy = 12/x

3x = 5*12 = 60
x = 20

so there are 20y  silver guppies in the tank.