7. charlie and dasha are roommates, and
they have a dog. if neither of them is
home, they hire someone to watch the
dog. charlie must go on business trips
every 6 months, while dasha must go on
business trips every 9 months. if they
both just got back from business trips,
how many months will it be before they
need to hire someone to look after the
dog again? explain your answer.

18 months

Step-by-step explanation:

First find the least common multiple.In case you don't know what that is its basically the number they have in common when you skip count by 6 and 9.Your answer would be 18.So that's your answer.

for this case we must apply distributive property to the following expression:

the distributive property states that:

then, when applying the property we have to multiply the -2 for each term within the parenthesis: