An effective multimedia presentation
adds off-topic information.
answers the research question
addresses only one perspective.
uses a lot of flashy media.

An effective multimedia presentation answers the research question.

Option B

Explanation:

Multi media presentation is the presentation of a topic which is presented using the animation and use of media which might be audio, video or both. This feature of the presentation makes it different and attractive for the people to see such a presentation. An effective multimedia presentation is such which tries to answer the questions on which the research of the topic is based.

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13