Ang earns $2,700 per month. He pays $600 a month on rent. What is the ratio of his rent to his monthly income?

The ratio of the rent ($600) to the income ($2700) is written as:

600 : 2700.

You need to reduce the ratio. Both 600 and 2700 are divisible by 3, and dividing them both by three, you get the following:

200 : 900.

This can be reduced further by dividing by 100.

2 : 9

So, Ang spends 2 dollars on rent for every 9 dollars he earns,