Last summer, Mr. Kim paid Johnny $45 each time he mowed the lawn. By the end of summer, Mr. Kim had paid Johnny a total amount of $270. Which equation could be used to find the number of times (n) Johnny mowed Mr. Kim's lawn last summer? ОА 45n = 270 OB 270n 45 ОС 270 -'n = 45 OD 45 + n = 270