At the start of an adventure game, ralph had 100 coins. at the end of the game, he had 415 coins. ralph earned 45 coins for each successful mission. assuming he did not lose or spend any coins, solving which equation will show how many successful missions ralph completed? a. 7x - 100 = 315 b. 7x + 100 = 415 c. 45x - 100 = 315 d. 45x + 100 = 415