
Kyle S. answered 06/09/17
Tutor
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(13)
Musical Math Tutor
Hi, Nykeemah.
We will let Carmen's number of messages be c.
If Juan sent 8 fewer than Carmen, he sent c - 8 messages.
Since Ruben sent 2 times as many as Juan, he sent 2(c-8) or 2c - 16 messages.
The sum of them all equals 140. That is...
c + (c - 8) + (2c - 16) = 140
Let's solve for c:
c + (c - 8) + (2c - 16) = 140
c + c - 8 + 2c - 16 = 140
4c - 24 = 140
4c - 24 + 24 = 140 + 24
4c = 164
c = 164/4 = 41
So, Carmen sent 41 messages.
Juan sent 8 fewer, so he sent 41 - 8 or 33 messages.
Ruben sent twice as many as Juan, so he sent 2*33 or 66 messages.
Then to check,
41 + 33 + 66 = 74 + 66 = 140