Can someone please help me with this, and give a thorough explanation?

x=68

Step-by-step explanation:

A. It’s asking what the last test must have to be (x) for all five tests to average out to an 80. This can be represent by:

(95+76+77+84+x)/5=80

The first four numbers are the existing test scores and x is the score you need. This is all divided by five so that you can find the average of all of these added together, which will equal 80, because that’s the grade you’re trying to get. Next, just solve for x:

= 95+76+77+84+x=80(5)

= 332+x=400

X=68

B. I got 74 for this one by using the same process as in part a, but I divided the left side by six and multiplied x by two: (95+76+77+84+2x)/6=80

But I’m not completely positive about this answer. A is definitely right though