How much alfalfa should be added to 60L of ostrich pellets to create a mix that is 32% alfalfa by volume?

I have no idea how to start this question. If I let x be the alfalfa and x+60 = 32 be the mix

2 answers

a / (a + 60) = .32

a = .32 a + 19.2

.68 a = 19.2
60/68*32 = 28.23L