consists
extends
passes
are
"Hiking through these mountain ranges is very challenging." The active verb is "is". There is also a gerund, "hiking" which serves as the subject of the sentence. The subject clause is "Hiking through these mountain ranges", so even though "hiking" is a verb form, a gerund, it is not the verb in this sentence; it is part of the subject clause.
The rest of the passage contains other types of verb clauses, so you need to study those until you understand them! (:
A.) First 5 terms are: 4(1) + 5, 4(2) + 5, 4(3) + 5, 4(4) + 5, 4(5) + 5 = 4 + 5, 8 + 5, 12 + 5, 16 + 5, 20 + 5 = 9, 13, 17, 21, 25
b.) 25th term = 4(25) + 5 = 100 + 5 = 105
sum of the first 25 terms = 25/2(9 + 105) = 25/2(114) = 285
c.) The sequence is an arithmetic sequence because, the sequence increases by addition of 4.
