Answer:
D. 21/2
Step-by-step explanation:
We simply have to evaluate the first three terms based on the progression's formula:
t= 1, the first term is 8, as we see:

t=2, the second term is 2, as we see:

t=3, the third term is 1/2, as we see:

The sum of the first 3 terms is then: 8 + 2 + 1/2 = 10 1/2
Among the answer choices, D. 21/2, which is 10 1/2.
5x+ 10= -4x -17
⇒ 5x+ 4x= -17 -10
⇒ 9x= -27
⇒ x= -27/9
⇒ x= -3
Final answer: x=-3~
Here's what I got for the first question.
Did you want answers for the second one? I couldn't read that part of the image very well, if you did.