Question

6th grade math

Answer 1

Answer:

She will replace both at the same time in 18 months

Step-by-step explanation:

The first thing you have to do to find when she will change them at the same time, is to try with multiples of both, untill they match.

Hall Closet = every 9 months

Air Filter = every 6 months

1) 9-18-27-36-45

2)6-12-18

We find that in the 18th month he will change both of them.

Answer 2

They will both be replaced the 18th month.