Write and solve an equation to find the value of x can someone explain too : )

let's recall that the sum of all interior angles in a triangle is 180°, so then

from the sentence, "tomorrow morning, akiko will arrive an hour late" depicts a third person perspective because it doesn't use any pronoun to replace akiko, the subject of the sentence, and it is in singular form since akiko is only one person.

i'm assuming that it's c.)   volcanoes built the mountains and earthquakes tore them down.