Spanish help? Thanks, only 2 questions ~ Use the correct form of "el" "la" "los" or "las"

Match each topic to the audience who would be most receptive to the topic. the audience is stay-at-home moms who are 30 to 40 years old. they are college-educated women who live in the suburbs. the audience is a group of male college students getting ready to graduate from college. they attend a large university in a big city. the audience is blue-collar workers who are 30 to 50 years old. they work in the steel industry in a small, rural community. the audience is retired men and women who are 70 to 80 years old. they live in a retirement community, and many of them have several grandchildren who live far away. the audience is a group of students getting ready to sign up for seventh-grade classes. they come from a wide range of intellectual levels, but many of the students travel extensively with their families. using a social networking website to connect with friends and family arrowright advantages of joining a labor union arrowright home schooling reform arrowright how to prepare for a job interview arrowright the importance of studying a foreign language arrowright reset

Choose the sentence that accurately expresses a hurt back. me duele la mano. me duele la espalda. me duele el cuello. me duele el brazo.

Achemist mixes 4 liters of one acid solution with 10 liters of a 40% solution, resulting in a 30% acid solution. what is the value of x, the acid concentration of the first solution