Answer:
Number of messages sent by Chau = 15
Number of messages sent by Kareem = 4 * 15 = 60
Number of messages sent by Jessica = 15 - 6 = 9
Explanation:
Let number of messages sent by Chau = c
Number of messages sent by Kareem = 4 times as Chau
= 4 * c = 4c
Number of messages sent by Jessica = 6 fewer messages than Chau
= c - 6
Total messages = 84
c + 4c + c - 6 = 84 {Combine like terms}
6c - 6 = 84 {Add 6 to both sides}
6c = 84 + 6
6c = 90 {Divide both sides by 6}
c = 90/6
c = 15
Number of messages sent by Chau = 15
Number of messages sent by Kareem = 4 * 15 = 60
Number of messages sent by Jessica = 15 - 6 = 9