Answer:
Number of messages Salma sent = 7
Number of messages Brian sent = 16
Number of messages Chang sent = 32
Step-by-step explanation:
Let
Number of messages Salma sent = n
Number of messages Brian sent = n + 9
Number of messages Chang sent = 2(n + 9)
Total messages sent = 55
n + (n + 9) + 2(n + 9) = 55
n + n + 9 + 2n + 18 = 55
4n + 27 = 55
4n = 55 - 27
4n = 28
n = 28/4
n = 7
Number of messages Salma sent = n = 7 messages
Number of messages Brian sent = n + 9 = n + 9 = 16 messages
Number of messages Chang sent = 2(n + 9)
= 2(7 + 9)
= 2(16)
= 32 messages
