what is the textual evidence for the theme of “a sound of thunder”? the theme is something that seems small can make a bigger difference than you think.

One cell phone plan charges $20 per month plus $0.15 per minute used. a second cell phone plan charges $35 per month plus $0.10 per minute used. write and solve an equation to find the number of minutes you must talk to have the same cost for both calling plans.