When is it appropriate to break the rule that requires subjects joined by and to use a plural verb

it is appropriate to break the rule that requires subjects joined by and to use a plural verb when either  and neither are subjects. They always take singular verb.

For example :

Either of us is capable of doing the job

It is appropriate to break the rule that requires subjects joined by and to use a plural verb when: the two subjects separated by and refer to the same person or thing. Examples are: Peanut butter and jelly is my favorite sandwich. Red beans and rice is my mom's favorite dish.

the correct answer is the following.

one of the groups i belong to is the boy scouts. this is a problem-solving group because it has tasks that we need to solve in order to other people in different activities such as the rescue of lost pets, or elder people in need.

the other group i belong to is kids pro environment, and is an information-sharing group that tries to create conscience about the risks and problems that generate pollution in our cities. we share information to other students and parents on the importance of keep our communities clean and our skies clear.