Answer:
Step-by-step explanation:
Didn't you mean "their cell phones?"
Represent the # of Scott's messages by s. Then Elsa sent s - 7 msgs, and Miguel sent 4(s - 7) msgs.
Then s + s - 7 + 4s - 28 = 103, and
6s - 35 = 103, or
6s = 138
Then s = 138/6, or s = 23.
Scott sent 23 msgs, Elsa sent 16 and Miguel sent 4(16), or 64 msgs.
Note that 23 + 16 + 64 = 103.