Question

3 out of 5 cubes are orange. If 12 cubes are orange, how many cubes are there in all?

Answer 1

We know that the ratio between the number of orange cubes and the number of all cubes it 3:5.

So, we can use a proportion like

`\text{unit ratio of orange cubes} : \text{unit ratio of all cubes} = \text{actual number of orange cubes} : \text{actual number of all cubes}`

Which means, if we let c be the number of cubes,

`3:5 = 12:c \iff c = (5\cdot 12)/(3) = 20`